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Biomedical subjects

Y Fukui

Publications and source records attributed to Y Fukui.

At least 145 records · Page 8Linked to original sources
PubMed1999

Identification of protein kinase B (PKB) as a phosphatidylinositol 3,4,5-trisphosphate binding protein in Dictyostelium discoideum.

We have searched for phosphatidylinositol (PI)-3,4,5-trisphosphate (PIP3) binding proteins in Dictyostelium discoideum using beads bearing a PIP3 analogue, PIP3-APB. One of the binding proteins with a molecular mass of 55 kDa was purified and its amino acid sequence was partially analyzed. Database searches showed that the analyzed sequence was identical to that of protein kinase B (PKB) of D. discoideum. The specific activity of D. discoideum PKB, when expressed together with constitutively active PI-3 kinase in mammalian cells, was elevated by about three-fold, suggesting that PKB could also act downstream of PI-3 kinase in Dictyostelium cells.

Amino Acid Sequence↗
PubMed1999

Identification of the major antioxidative metabolites in biological fluids of the rat with ingested (+)-catechin and (-)-epicatechin.

(+)-Catechin and (-)-epicatechin are known to be biologically effective antioxidants present in the human diet, particularly in wine and tea. We studied the metabolism of these compounds to elucidate the truly active structures in biological fluids by their oral administration to rats. Without any treatment with beta-glucuronidase and sulfatase, a pair of metabolites were detected at much higher concentrations in the plasma, bile, and urine than the originally ingested compounds. Each major metabolite found in the plasma at the highest concentration was excreted in both the bile and urine, and was purified from urine. Their chemical structures were established to be (+)-catechin 5-O-beta-glucuronide and (-)-epicatechin 5-O-beta-glucuronide by MS and NMR analyses. These glucuronide conjugates exhibited high antioxidative activities as superoxide anion radical scavengers like their parent compounds. It is concluded that (+)-catechin 5-O-beta-glucuronide and (-)-epicatechin 5-O-beta-glucuronide are the biologically active in vivo structures of the ingested polyphenolic antioxidants.

Animals↗
PubMed1999

Emotion space under conditions of perceptual ambiguity.

This study examined whether a two-dimensional structure of emotion could be found under the condition of perceptual ambiguity, using a stereoscopic procedure. Two expressions of depicted emotion were presented simultaneously to each different eye of the subjects. Multidimensional scaling yielded results suggesting that the dimensional structure such as valence and arousal was evident even under such an unusual condition as that of the current study.

Adult↗
PubMed1999

The importance of the plasma amino acid molar ratio in patients with biliary atresia.

BACKGROUND: Plasma amino acid patterns and the therapeutic benefits of amino acid supplements are not examined well in postoperative patients with biliary atresia (BA). This study aimed to investigate profiles of the amino acid molar ratio, the Fischer molar ratio (FR, valine + leucine + isoleucine/phenylalanine + tyrosine), and relationships with other nutritional parameters and to assess the efficacy of enteral nutrient preparations for hepatic failure in patients with BA. METHODS: In study 1 profiles of FR were analyzed in 24 patients with BA (aged 3 to 12 years) in the postoperative period and compared with liver function tests and anthropometric measures. In study 2 10 patients with BA with a FR < 2.0 were begun on a dietary regimen consisting of an ordinary diet supplemented with a branched-chain amino acid-enriched elemental diet. RESULTS: Study 1: In jaundiced patients with total bilirubin levels > 2.0 mg/dL the FR remained below 2.0 throughout the period of observation, in contrast with nonjaundiced patients. The FR was closely related to the levels of serum albumin and plasma rapid turnover proteins and anthropometric measures as well as biochemical data reflecting intrinsic liver function. Study 2: A significant increase in rapid turnover proteins and improvement of general status were noted concurrently with an increase of the FR. CONCLUSIONS: The FR indicates a combination of nutritional status and intrinsic liver function in post-operative BA patients. The FR is a useful parameter in conducting nutritive therapy with a branched-chain amino acid-enriched elemental diet in those patients.

Adolescent↗
PubMed1999

Effects of ethanol and/or cardiovascular drugs on cocaine- and methamphetamine-induced fatal toxicities in mice.

The antidotal effects of antihypertensive cardiovascular (CV) drugs against cocaine (COCA)- and methamphetamine (MA)-induced fatal toxicities were examined in mice. Considering the previously-reported favorable interactions, the effects of CV drugs against combined COCA-ethanol (EtOH) or MA-EtOH toxicities were also evaluated. COCA (75 mg/kg) or MA (18 mg/kg) was administered 5 min after an injection of CV drugs, with or without EtOH (3 g/kg); all drugs were injected intraperitoneally. The CV drugs used were 10 mg/kg diltiazem (DIL), 5 mg/kg nimodipine (NIMO) and 5 mg/kg nitrendipine (NITRE) as calcium channel blockers, 5 mg/kg prazosin (PRA) and 5 mg/kg phentolamine (PHEN) as alpha-adrenergic blocking agents, 10 mg/kg propranolol (PRO) as a beta-adrenergic blocking agent, and 10 mg/kg enalapril (ENA) as an angiotensin converting-enzyme inhibitor. In both the COCA (n = 10) and MA (n = 6) groups, regardless of EtOH or CV drug cotreatment, the fatalities could be divided into the early and late deaths, depending on the survival times, the presence of a temporary recovery from acute toxic symptoms such as observable respiratory and locomotive symptoms, and the presence of the drugs (COCA or MA) in blood samples. The acute toxic symptoms included seizures in both the COCA and MA groups, but they were generally suppressed by EtOH regardless of the mortality rate. Some of the CV drugs, such as PRA and PHEN in the COCA groups and DIL, NIMO, NITRE, PRA and PHEN in the MA groups, also suppressed the seizures. The mortality rate was attenuated by PRA in the COCA groups, and by NIMO, NITRE, PRA and PHEN in the MA groups. In the groups cotreated with EtOH, which has been reported to exacerbate the COCA- and MA-induced cardiotoxicity, the frequency of late deaths was increased. Nevertheless, antidotal effects due to NIMO, NITRE, PRA and ENA in the COCA-EtOH groups, and NIMO, NITRE and PRA in the MA-EtOH groups were observed.

Animals↗
PubMed1998

Highly restricted T cell repertoire shaped by a single major histocompatibility complex-peptide ligand in the presence of a single rearranged T cell receptor beta chain.

The T cell repertoire is shaped by positive and negative selection of thymocytes through the interaction of alpha/beta-T cell receptors (TCR) with self-peptides bound to self-major histocompatibility complex (MHC) molecules. However, the involvement of specific TCR-peptide contacts in positive selection remains unclear. By fixing TCR-beta chains with a single rearranged TCR-beta irrelevant to the selecting ligand, we show here that T cells selected to mature on a single MHC-peptide complex express highly restricted TCR-alpha chains in terms of Valpha usage and amino acid residue of their CDR3 loops, whereas such restriction was not observed with those selected by the same MHC with diverse sets of self-peptides including this peptide. Thus, we visualized the TCR structure required to survive positive selection directed by this single ligand. Our findings provide definitive evidence that specific recognition of self-peptides by TCR could be involved in positive selection of thymocytes.

Amino Acid Sequence↗
PubMed1998

Effects of dietary Pi on the renal Na+-dependent Pi transporter NaPi-2 in thyroparathyroidectomized rats.

Dietary Pi and parathyroid hormone (PTH) are two most important physiological and pathophysiological regulators of Pi re-absorption in the renal proximal tubule. Effects of dietary Pi on Na+/Pi co-transporter NaPi-2 were investigated in thyroparathyroidectomized (TPTX) rats. NaPi-2 protein and mRNA in the kidney cortex of TPTX rats were increased approximately 3.8- and 2.4-fold in amount respectively compared with those in the sham-operated animals. Administration of PTH to the TPTX rats resulted in a decrease in the amount of NaPi-2 protein, but not in the abundance of NaPi-2 mRNA. Deprivation of dietary Pi in the TPTX rats did not affect the amount of NaPi-2 mRNA and protein. In the Pi-deprived TPTX rats, feeding of a high-Pi diet resulted in marked decreases in Pi transport activity and the amount of NaPi-2 protein in the superficial nephrons. Immunohistochemical analysis demonstrated that administration of PTH to TPTX rats resulted in a decrease in NaPi-2 immunoreactivity from both superficial and juxtamedullary nephrons within 4 h. Switching TPTX animals from a low-Pi diet to the high-Pi diet decreased NaPi-2 immunoreactivity from superficial nephrons, but not from juxtamedullary nephrons, within 4 h. These results suggest that dietary Pi could regulate the amount of NaPi-2 protein in the superficial nephrons in a PTH-independent manner.

Animals↗
PubMed1998

Quantitative analysis of the T cell repertoire selected by a single peptide-major histocompatibility complex.

The positive selection of CD4+ T cells requires the expression of major histocompatibility complex (MHC) class II molecules in the thymus, but the role of self-peptides complexed to class II molecules is still a matter of debate. Recently, it was observed that transgenic mice expressing a single peptide-MHC class II complex positively select significant numbers of diverse CD4+ T cells in the thymus. However, the number of selected T cell specificities has not been evaluated so far. Here, we have sequenced 700 junctional complementarity determining regions 3 (CDR3) from T cell receptors (TCRs) carrying Vbeta11-Jbeta1.1 or Vbeta12-Jbeta1.1 rearrangements. We found that a single peptide-MHC class II complex positively selects at least 10(5) different Vbeta rearrangements. Our data yield a first evaluation of the size of the T cell repertoire. In addition, they provide evidence that the single Ealpha52-68-I-Ab complex skews the amino acid frequency in the TCR CDR3 loop of positively selected T cells. A detailed analysis of CDR3 sequences indicates that a fraction of the beta chain repertoire bears the imprint of the selecting self-peptide.

Animals↗
PubMed1998

Specific detection of phosphatidylinositol 3,4,5-trisphosphate binding proteins by the PIP3 analogue beads: an application for rapid purification of the PIP3 binding proteins.

Phosphatidylinositol (PI) 3-kinase is known as one of the key molecules involved in the various biological events such as vesicle trafficking, cytoskeletal rearrangements and cell survival. T clarify the molecular basis underlying these events, we have tried to identify the proteins that can interact with phosphatidylinositol 3,4,5-trisphosphate (PIP3), the lipid product of PI3-kinase. Using a new PIP3 analogue, PIP3-APB, we synthesized an affinity column for PIP3 binding proteins. This enabled us to purify and identify several PIP3 binding proteins such as Tec tyrosine kinase, Gap1m, and Akt, as the candidates for the downstream molecules of PI3-kinase. All of these proteins contain PH domains, possible binding sites for phospholipids. Studies with various deletion mutants of Tec or Gap1m revealed that their PH domains are indeed the binding sites for PIP3. These results demonstrate that this PIP3-analogue binds various PIP3 binding proteins with high specificity and may be useful to elucidate the downstream mechanisms of PI3-kinases-mediated signaling pathways.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Density dependent elevation of phosphatidylinositol-3 kinase level in rat 3Y1 cells.

We have explored the levels of phosphatidylinositol-3 kinase protein during culture of rat 3Y1 cells. Confluent cell cultures exhibited a higher level of phosphatidylinositol-3 kinase compared with that of growing cells. After replating of the cells on fresh dishes, the level of phosphatidylinositol-3 kinase returned to that of growing cells within 24h. This density-dependent regulation of the phosphatidylinositol-3 kinase level was not lined to cell growth, because growth arrest by serum starvation did not cause elevation of the phosphatidylinositol-3 kinase level. Northern blotting analysis revealed that this regulation was based on the transcriptional level. After cell growth was arrested by contact inhibition, elevation of the level of phosphatidylinositol-3,4,5-trisphosphate was detected suggesting that phosphatidylinositol-3 kinase was activated in these cells. These effects were not seen in src-transformed 3Y1 cells, suggesting that this regulation was lost in transformed cells.

Animals↗
PubMed1998

An endogenously processed self peptide and the corresponding exogenous peptide bound to the same MHC class II molecule could be distinct ligands for TCR with different kinetic stability.

Immunization with self peptides often elicits activation of CD4+ T cells in vivo. Although such peptides have been suggested to be derived from minor self determinants or self antigens sequestered from the immune system, we found that immunization with Ealpha peptide (Ealpha52-68), a major self determinant bound to I-Ab molecules, elicits an immune response in Ealpha-transgenic C57BL/6 (Ealpha-B6) mice where Ealpha52-68 is endogenously processed and presented by I-Ab molecules in the thymus and periphery. To better understand this response, a panel of T cell hybridomas raised against exogenous Ealpha52-68 were analyzed for their reactivity to spleen cells from Ealpha-B6 mice. Some hybridomas were stimulated with Ealpha-B6 spleen cells in the absence of exogenous Ealpha52-68, whereas others were not stimulated with them. The Ealpha52-68/I-Ab complex recognized by the TCR that is expressed on the hybridoma with reactivity to Ealpha-B6 spleen cells was found to be quite stable, whereas the complex recognized by the TCR on the hybridoma specific for the exogenous Ealpha52-68 lost the stimulation activity by incubation the complex at 37 degrees C for 10 min. Stimulation experiments using extensively substituted Ealpha analogue peptides suggested that amino acid residues at positions 57, 58, 60 and 62 of Ealpha52-68 are involved in the interaction with TCR recognizing the Ealpha52-68/I-Ab complex expressed on Ealpha-B6 spleen cells. While amino acid substitutions at positions 60 and 62 also affected the recognition of TCR specific for exogenous Ealpha52-68, all or many amino acid substitutions were allowed at position 58 or 57, respectively, without impairing the TCR recognition. Taken together, these results suggest that endogenously processed self peptide and the corresponding exogenous peptide bound to the same MHC class II molecule could be distinct TCR ligands with different kinetic stability and probably with different configuration.

Animals↗
PubMed1998

Successful laparoscopic cholecystectomy in a child with upper transverse scarring: report of a case.

Laparoscopic cholecystectomy (LC) was safely performed for cholelithiasis in a 4-year-old boy who had a long transverse operative scar in the upper abdomen as a result of intestinal surgery performed during the neonatal period. The adhesions beneath the scar were sharply divided and sometimes coagulated, and additional working ports were subsequently placed as the adhesiolysis proceeded. LC was performed in the usual fashion using 5-mm titanium clips, and his postoperative course was uneventful. This case report serves to demonstrate that laparoscopic surgery is feasible even for pediatric patients who have undergone previous major intraabdominal surgery.

Child, Preschool↗
PubMed1998

Regulation of the PepT1 peptide transporter in the rat small intestine in response to 5-fluorouracil-induced injury.

BACKGROUND & AIMS: The oligopeptide transport system of the small intestine is resistant to mucosal injury. The mechanism of this resistance was investigated by examining the activity level and expression of the peptide transporter PepT1 in the intestine of rats treated with 5-fluorouracil. METHODS: The expression and localization of PepT1 were examined by immunoblot analysis of brush border membrane vesicles and immunohistochemical analysis of intestinal sections with PepT1-specific rabbit polyclonal antibodies. Also, Northern blot analysis was used for the expression of PepT1 messenger RNA (mRNA). RESULTS: Although the amounts of sucrase and an Na+-dependent glucose transporter protein in intestinal vesicles decreased markedly after 5-fluorouracil treatment, the amount of PepT1 protein remained largely unaffected. Immunohistochemical analysis also showed that the PepT1 immunoreactivity level was preserved in the brush border membrane of the remaining villi of 5-fluorouracil-treated rats. Levels of amino acid, glucose, and phosphate transporter mRNAs were profoundly depressed in 5-fluorouracil-treated animals, whereas the level of PepT1 mRNA conversely increased. CONCLUSIONS: The resistance of intestinal peptide transport to tissue injury may be attributable to increased synthesis of PepT1 rather than to a change in the kinetic properties of the residual absorbing cells.

Animals↗
PubMed1998

Endoscopic variceal ligation in the management of gastroesophageal varices in postoperative biliary atresia.

BACKGROUND/PURPOSE: Gastroesophageal variceal bleeding is a serious and difficult problem in the long-term management of biliary atresia (BA). Recently, endoscopic approaches have been attempted to manage this problem. The authors have attempted endoscopic variceal ligation (EVL), a less invasive procedure than endoscopic sclerotherapy. METHODS: In the past 5 years, 66 EVL procedures using standard flexible endoscope with a diameter of 9 mm (type p-30, XQ200, or XQ240; Olympus, Tokyo, Japan) were performed in 30 separate sessions on 11 postoperative BA patients. The mean age of the children was 7.8 (range, 3 to 15) years. The EVL device was a small elastic O-ring or a loop ligator. RESULTS: EVL was performed for emergency hemostasis in two patients and prophylaxis for impending rupture in nine with large, blue varices, or with red spots on the variceal surface. During the initial procedure, all varices were ligated successfully, and reduction in size was noted. Of eight patients who were examined 7 to 14 days after treatment, seven (87.5%) had improved. Eight of 11 patients (72.7%) were finally cured or at least had improved after one to seven sessions of EVL. However, three patients did not show improvement after four to seven sessions because of the reappearance of the varices, development of distal lesions such as gastric varices, and acute gastric mucosal lesions. A technical complication encountered was a slippage of the O-ring in one patient. A technical difficulty was seen in ligating the giant gastric varix in one patient. There was no deterioration of liver function induced by EVL in this entire series. CONCLUSIONS: EVL is an effective and feasible treatment of gastroesophageal varices in postoperative BA patients. However, reappearance or reactivation of the varices or emergence of the more distal lesions is likely to occur even after repeated EVL.

Adolescent↗
PubMed1998

Brain beta-endorphin immunoreactivity as an index of cocaine and combined cocaine-ethanol toxicities.

The present study examines alterations in the cytoplasmic immunoreactivity of brain beta-endorphin, an endogenous opioid peptide regarded as the mediator of both euphoria and antinociceptive systems, in relation to toxicities due to cocaine and combined cocaine-ethanol. Beta-endorphin-immunoreactive cells were visualized and counted in adjacent sections from male rat brains at the level of the arcuate nucleus. In this region, cytoplasmic beta-endorphin immunoreactivity is prevalent. An intraperitoneal injection of cocaine (75 or 15 mg/kg) was given 15 min after an intraperitoneal injection of 3 g/kg ethanol or vehicle. With a fatally toxic dose (75 mg/kg) of cocaine, the number of neurons exhibiting cytoplasmic beta-endorphin immunoreactivity (immunoreactive nerve cells) was significantly increased immediately after the drug administration. Ethanol further enhanced the effects of both 15 and 75 mg/kg of cocaine. When the immunoreactivity was visually estimated by computer imaging analysis, lightly stained, weakly immunoreactive cells with photographic light absorption values greater than 50% were enhanced in the cocaine-ethanol groups compared to the cocaine only groups. Fatal toxicities were only observed in the groups treated with the high cocaine doses (75 mg/kg), with or without ethanol. In these groups, the number of strongly immunoreactive cells had increased significantly compared to the other groups. In the group treated with the high cocaine dose (75 mg/kg) plus ethanol, an increased frequency of late deaths that occurred over 1 h after the drug administration was observed, together with a decreased severity of cocaine-induced seizures and an early enhancement of weakly immunoreactive cells. Unlike the strongly immunoreactive cells, the weakly immunoreactive cells appeared to be continuously enhanced, based on an experiment examining beta-endorphin immunoreactivity at 24 h after an injection of 50 mg/kg cocaine.

Animals↗
PubMed1998

Development of peptide vaccines inducing production of neutralizing antibodies against HIV-1 viruses in HLA-DQ6 mice.

Peptide vaccines against HIV-1 were prepared according to the cassette theory that we had proposed previously. An amino acid sequence of B subtype consensus of the HIV-1 V3 region was introduced into the MHC binding component with a supermotif for various MHC class II. The peptide vaccines induced T-cell responses in the DQ6 mice in which only DQ6 molecules were expressed as MHC class II. By contrast, an original V3 peptide including the consensus sequence was non-immunogenic in the DQ6 mice. Antibodies obtained from the DQ6 mice immunized with the peptide vaccines neutralized laboratory B subtype strains of HIV-1 in vitro. It may be anticipated that these peptide vaccines protect infection of HIV-1 in DQ6 positive individuals.

AIDS Vaccines↗