Biomedical subjects

E Ito

Publications and source records attributed to E Ito.

At least 19 recordsLinked to original sources

PubMed1999

Optical detection of synaptically induced glutamate transport in hippocampal slices.

Although it has long been believed that glial cells play a major role in transmitter uptake at synapses in the CNS, the relative contribution of glial and neuronal cells to reuptake of synaptically released glutamate has been unclear. Recent identification of the diverse glutamate transporter subtypes provides an opportunity to examine this issue. To monitor glutamate transporter activity, we optically detected synaptically induced changes of membrane potential from hippocampal CA1 field in slice preparations using a voltage-sensitive dye, RH155. In the presence of ionotropic glutamate-receptor blockers, synaptic inputs gave rise to a slow depolarizing response (SDR) in the dendritic field. The amplitude of SDR correlated well with presynaptic activities, suggesting that it was related to transmitter release. The SDR was found to be caused by the activities of glutamate transporters because it was not affected by blockers for GABAA, nACh, 5-HT3, P2X, or metabotropic glutamate receptors but was greatly reduced by dihydrokainate (DHK), a specific blocker for GLT-1 transporter, and by D, L-threo-beta-hydroxyaspartate (THA), a blocker for EAAC, GLAST, and GLT-1 transporters. When SDR was detected with RH482 dye, which stains both glial and neuronal cells, 1 mM DHK and 1 mM THA were equally effective in suppressing SDR. The SDR was very small in GLT-1 knockout mice but was maintained in gerbil hippocampi in which postsynaptic neurons were absent because of ischemia. Because GLT-1 transporters are exclusively expressed in astrocytes, our results provide direct evidence that astrocytes play the dominant role in sequestering synaptically released glutamate.

ATP-Binding Cassette Transporters↗

PubMed1999

A core promoter and a frequent single-nucleotide polymorphism of the mismatch repair gene hMLH1.

The hMLH1 gene encodes a protein that is involved in the DNA mismatch repair system. The coding region of the hMLH1 gene has been known to be mutated in a subset of patients with hereditary nonpolyposis colorectal cancer (HNPCC). Our current research characterized the promoter region of the hMLH1 gene and searched for mutations correlating to HNPCC. Utilizing the oligo-capping method, major transcription start sites of the hMLH1 gene were mapped at two locations. The core promoter region of about 180 bp was determined by the luciferase assay of serial deletion mutants. Although we did not find any pathogenic mutation in the hMLH1 promoter region by PCR-SSCP, we found a single-nucleotide polymorphism at position -93 nt from the adenine residue of the start codon. By PCR-RFLP analysis with Pvu II for this polymorphism, we detected LOH in four tumors from three patients. An easy detection of this polymorphism with PCR-RFLP and high incidence ( approximately 50%) of informative cases make this polymorphism a suitable marker for the detection of hMLH1 allelic losses.

3T3 Cells↗

PubMed1999

Molecular cloning and functional characterization of a new Cap'n' collar family transcription factor Nrf3.

The NF-E2-binding sites or Maf recognition elements (MARE) are essential cis-acting elements in the regulatory regions of erythroid-specific genes recognized by the erythroid transcription factor NF-E2, composed of p45 and MafK. Recently, two p45-related factors Nrf1 and Nrf2 were isolated, and they are now collectively grouped as the Cap'n' collar (CNC) family. CNC factors bind to MARE through heterodimer formation with small Maf proteins. We report here the identification and characterization of a novel CNC factor, Nrf3, encoding a predicted 73-kDa protein with a basic region-leucine zipper domain highly homologous to those of other CNC proteins. In vitro and in vivo analyses showed that Nrf3 can heterodimerize with MafK and that this complex binds to the MARE in the chicken beta-globin enhancer and can activate transcription. Nrf3 mRNA is highly expressed in human placenta and B cell and monocyte lineage. Chromosomal localization of human Nrf3 is 7p14-15, which lies near the hoxA gene locus. As the genetic loci of p45, nrf1, and nrf2 have been mapped close to those of hoxC, hoxB, and hoxD, respectively, the present study strongly argues for the idea that a single ancestral gene for the CNC family members may have been localized near the ancestral Hox cluster and have diverged to give rise to four closely related CNC factors through chromosome duplication.

Amino Acid Sequence↗

PubMed1999

Two short sequences have positive effects on the human p27Kip1 gene transcription.

The cyclin-dependent kinase (Cdk) inhibitor p27Kip1 plays an important role in the progression from G1 to S phase in the cell cycle. To study the activities of its promoter and other regulatory elements, we have cloned and characterized the 5'-flanking region of the human p27Kip1 gene. This region, about 3kb in length, is GC-rich and shares homology with that of the mouse p27Kip1 gene. Transcription start points (tsp) determined by the oligo-capping method are mapped in two regions, the cluster I (-479 to -403) and cluster II (-280 to -273). The cluster I was the primary functional site in transcription initiation. The luciferase activities of serial deletion mutants indicated that two short sequences (-581 to -557 and -556 to -526) had positive effects on transcription. The gel shift assay showed that factors in HeLa nuclear extract bound to these sequences. Sp1 was the major binding factor to the sequence of -556 to -526, wheres yet unidentified positive factors bound to the sequence of -581 to -557.

Base Sequence↗

PubMed1999

Effects of electrical stimulation of the tentacular digits of a slug upon the frequency of electrical oscillations in the procerebral lobe.

To find the primary mechanism for the frequency changes of electrical oscillations in the procerebral (PC) lobe of a slug, we electrically stimulated the tip, middle and basal regions of the digits of the superior and inferior tentacles and recorded the local field potentials from the PC lobe. Stimuli to the middle and basal regions of the digits of the inferior tentacle significantly decreased the frequency of electrical oscillations in the PC lobe, whereas those to the tip regions of the digits of the inferior tentacle and all regions of the digits of the superior tentacle increased it. These findings suggest that the change in the frequency of electrical oscillations in the PC lobe depends on the excited region in the digits, providing the first presentation of the physiological difference in the olfactory function between the superior and inferior tentacles.

Animals↗

PubMed1998

Climate and vegetation history of the midcontinent from 75 to 25 ka: A speleothem record from crevice cave, missouri, USA

Four Missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago (ka). The thorium-230-dated records reveal that between 75 and 55 ka, the midcontinental climate oscillated on millennial time scales between cold and warm, and vegetation alternated among forest, savanna, and prairie. Temperatures were highest and prairie vegetation peaked between 59 and 55 ka. Climate cooled and forest replaced grassland at 55 ka, when global ice sheets began to build during the early part of Marine Oxygen Isotope Stage 3.

Journal Article↗

PubMed1998

Marginal benefit/disadvantage of granulocyte colony-stimulating factor therapy after autologous blood stem cell transplantation in children: results of a prospective randomized trial. The Japanese Cooperative Study Group of PBSCT.

In this prospective trial, a total of 74 children who were scheduled to undergo high-dose chemotherapy followed by autologous peripheral blood stem cell transplantation (PBSCT) were prospectively randomized at diagnosis to evaluate the effectiveness of exogenous granulocyte colony-stimulating factor (G-CSF) treatment in accelerating hematopoietic recovery after PBSCT. The diagnosis included acute lymphoblastic leukemia (ALL) (n = 27), neuroblastoma (n = 29), and miscellaneous solid tumors (n = 18). Eligibility criteria included (1) primary PBSCT, (2) chemotherapy-responsive disease, and (3) collected cell number >1 x 10(5) colony-forming unit-granulocyte-macrophage (CFU-GM)/kg and >1 x 10(6) CD34(+) cells/kg patient's body weight. After applying the above criteria, 11 patients were excluded due to disease progression before PBSCT (n = 6) or a low number of harvested cells (n = 5), leaving 63 patients for analysis; 32 patients in the treatment group (300 microg/m2 of G-CSF intravenously over 1 hour from day 1 of PBSCT) and 31 in the control group without treatment. Two distinct disease-oriented high-dose regimens without total body irradiation consisted of the MCVAC regimen using ranimustine (MCNU, 450 mg/m2), cytosine arabinoside (16 g/m2), etoposide (1.6 g/m2), and cyclophosphamide (100 mg/kg) for patients with ALL, and the Hi-MEC regimen using melphalan (180 mg/m2), etoposide (1.6 g/m2), and carboplatinum (1.6 g/m2) for those with solid tumors. Five patients (two in the treatment group and three in the control group) were subsequently removed due to protocol violations. All patients survived PBSCT. The median numbers of transfused mononuclear cells (MNC), CD34(+) cells, and CFU-GM were, respectively, 4.5 (range, 1 to 19) x 10(8)/kg, 8.0 (1.1 to 25) x 10(6)/kg, and 3.7 (1.2 to 23) x 10(5)/kg in the treatment group (n = 30) and 2.9 (0.8 to 21) x 10(8)/kg, 6.3 (1.1 to 34) x 10(6)/kg, and 5.5 (1.3 to 37) x 10(5)/kg, respectively, in the control group (n = 28), with no significant difference. After PBSCT, the time to achieve an absolute neutrophil count (ANC) of >0.5 x 10(9)/L in the treatment group was less than that in the control group (median, 11 v 12 days; the log-rank test, P =.046), although the last day of red blood cell (RBC) transfusion (day 11 v day 10) and the duration of febrile days (>38 degrees C) after PBSCT (4 v 4 days) were identical in both groups. However, platelet recovery to >20 x 10(9)/L was significantly longer in treatment group than control group (26 v 16 days; P =.009) and >50 x 10(9)/L tended to take longer in the treatment group (29 v 26 days; P =.126), with significantly more platelet transfusion-dependent days (27 v 13 days; t-test, P =.037). When patients were divided into two different disease cohorts, ALL patients showed no difference in engraftment kinetics between the G-CSF treatment and control groups, while differences were seen in those with solid tumors. We concluded that the marginal clinical benefit of 1 day earlier recovery of granulocytes could be offset by the delayed recovery of platelets. We recommend that the routine application of costly G-CSF therapy in children undergoing PBSCT should be seriously reconsidered.

Adolescent↗

PubMed1998

Effect of percutaneous transvenous mitral commissurotomy on postexercise breathlessness as determined by ventilation during recovery from constant workload exercise.

We evaluated the effect of percutaneous transvenous mitral commissurotomy (PTMC) on ventilatory variables and dyspnea during recovery from a 6-minute submaximal constant workload exercise, and showed that the decrease in postexercise ventilation after PTMC was closely related to improvement in postexercise dyspnea after PTMC. Ventilation during recovery from submaximal constant workload exercise is related to postexercise breathlessness and can be used to assess the effectiveness of therapeutic interventions.

Adult↗

PubMed1998

Enhancement of cell death due to decrease in Mg2+ uptake by OmpC (cation-selective porin) deficiency in ribosome modulation factor-deficient mutant.

Ribosome modulation factor (RMF) is involved in stabilization of ribosomes during the transition from exponential growth to the stationary growth phase in Escherichia coli. A deficiency of RMF is known to reduce cell viability. Overaccumulation of spermidine also leads to a decrease in cell viability and to a decrease in the synthesis of RMF and of the cation-selective porin OmpC. Thus, a decrease in RMF levels may be involved in the decreased cell viability caused by excess spermidine. Because spermidine also influences the expression of OmpC, we examined whether OmpC deficiency enhances the cell death caused by RMF deficiency. The ompC mutant by itself did not affect protein synthesis or cell viability, but the double rmf ompC mutant produced a much larger decrease in protein synthesis and cell viability than did the single rmf mutant. There was also a decrease in the amount of ribosomes and in the Mg2+ content in the double rmf ompC mutant, and cell viability could be partially restored by the addition of Mg2+ to the growth medium. RMF deficiency was found to inhibit the synthesis of another cation-selective porin OmpF. Thus, the double rmf ompC mutant is deficient in both OmpC and OmpF, which probably accounts for the pronounced decrease in Mg2+ uptake in this mutant. The results indicate that both RMF and Mg2+, acting through stabilization of ribosomes, are important for cell viability at the stationary growth phase.

Bacterial Outer Membrane Proteins↗

PubMed1998

Sensory preconditioning for feeding response in the pond snail, Lymnaea stagnalis.

We demonstrated a sensory preconditioning in the pond snail, Lymnaea stagnalis. An appetitive sucrose solution (a conditioned stimulus: CS1) and weak vibration (another conditioned stimulus: CS2) were first associated, and then the CS2 and an aversive KCl solution (an unconditioned stimulus: UCS) were done. To build the conditioning, two different training procedures, spaced and massed, were examined. After the both training, the sensory preconditioning was built: significantly fewer feeding response to the CS1 became elicited; slower latency to the first bite to the CS1 was induced. No significant differences on the memory retention between these training procedures were found in the sensory preconditioning.

Animals↗

PubMed1998

The entropy generation in visual-pigment system by the absorption of light.

We first showed a general theory that reception of information from the outside in a receptor system is accompanied both by an inflow of entropy and by a generation of entropy depending on the reliability of the actual reception mechanism. Then, considering a case for the absorption of light by the visual-pigment system of visual cell, we calculated the time(t)-dependent change in the number N2(t) of excited visual-pigments to obtain the entropy increase. We thus arrived at the following four conclusions: (1) One or two photons can be detected with a reliability of at least 54%; (2) In compensation for this detection, entropy > 1.12 x log2 is generated; (3) An incident photon of frequency v from a ligh source of temperature Ts yields an entropy of hv/Ts; and (4) Depending on the characteristics of the visual-pigment system, another entropy being different from (2) is generated in proportion to N2(t).

Absorption↗

PubMed1998

Identification of the hydrophobic amino acid residues required for heme assembly in the rhizobial oxygen sensor protein FixL.

Rhizobial FixL is a novel heme protein, which senses environmental oxygen tension and directs signal transduction via protein phosphotransfer. To identify the essential residues for heme assembly in Rhizobium meliloti FixL, we individually replaced the 18 invariant hydrophobic amino acid residues (F, I, L, and V) in the heme-containing domain with alanine and histidine. Spectroscopic measurements of the soluble fractions from fixL recombinant Escherichia coli revealed that V152, F162, F170, I172, L185, F226, L230, and F243 as well as the proximal ligand H194 were indispensable for heme assembly. Autoxidation rates of purified I209H, I210A, and I210H were 65-fold, 15-fold, and 15-fold, respectively, faster than that of the wild type, although they retained heme in the protein. The absorption peak in the Soret region of the ferric I209H or I210H was red-shifted, suggesting that the ferric heme is a hexa-coordinate form in these mutants.

Amino Acid Sequence↗

PubMed1998

Promoter analysis of the human mismatch repair gene hMSH2.

The human DNA mismatch repair gene homologue hMSH2 is involved in hereditary nonpolyposis colorectal cancer. We isolated and characterized the 5' upstream region, about 4.4kbp, of the hMSH2 gene. This region contains CpG islands and a number of elements involved in constitutive expression, but there is no TATA-box nearby the transcription start points. This is the typical structure for many promoters of housekeeping genes. Alu sequences and mononucleotide repeats are clustered in this region and there are two transcription start points. Deletion analysis revealed that less than 300bp was sufficient to initiate transcription. Although no mutation that influences promoter activity of this region was found, a polymorphism was detected by PCR-RFLP analysis. Because informative cases (C/T heterozygous) were relatively high ( approximately 30%), this polymorphism is suitable for a marker to examine allelic losses.

Alleles↗

PubMed1998

Isolation and characterization of the 5' region of the human mismatch repair gene hPMS1.

The hPMS1 gene encodes a mutL homolog that is implicated in DNA mismatch repair and was found to be mutated in the germline of a patient with hereditary nonpolyposis colorectal cancer (HNPCC). To understand transcriptional regulation and to perform mutational analysis in the promoter region, we cloned and characterized the genomic sequence of the 5' region of the gene. hPMS1 has an intron upstream of the initiation codon. There were several transcripts with alternative splicing sites and multiple transcriptional start sites. The cloned 1.4-kbp fragment of the 5' region contains a CpG island but no TATA-boxes, typical for promoters of housekeeping genes. The promoter activity of the fragment was almost equal to that of the SV40 early promoter. Deletion analysis showed that about a 300-bp region was sufficient to initiate transcription. Although we searched for mutations in the hPMS1 promoter region in HNPCC kindreds, neither germline nor somatic mutations were detected. However, we found a highly informative polymorphism in the first exon that is useful for searching allelic losses because no polymorphic changes in hPMS1 have been reported previously.

Alleles↗

PubMed1998

Active platelet movements on hydrophobic/hydrophilic microdomain-structured surfaces.

The early motion and interaction of platelets on a microdomain-structured block copolymer surface composed of 2-hydroxyethyl methacrylate (HEMA)-styrene were analyzed and compared with those on a compositionally identical random copolymer, homopolymer poly (HEMA) (hydrophilic) and polystyrene (hydrophobic) surfaces. Contacting platelets were quantitatively more active, with motions including rolling, detachment, oscillatory vibration, and change of direction only on the HEMA-St block copolymer surface. Active platelet movements were observed for long time periods (>20 min) on HEMA-St block copolymer surfaces and were distinct from those for inert PSt latex particles on these same surfaces, demonstrating that platelet movements were not due to physical forces such as convection, hydrophobic interactions, or microbrownian movement. To study the cause and mechanism underlying the platelet movements, platelets treated with an adenosine triphosphate (ATP) synthesis inhibition, NaN3, or a membrane skeleton-disrupting chemical agent, dibucaine, were also studied on these surfaces. Both treatments reduced platelet movement and demonstrated that platelets in contact with the HEMA-St block copolymer surface require metabolic processes consuming ATP and involve dynamics of their membrane skeleton. These energy-consuming active movements might explain the previously observed lower platelet activation and low thrombogenicity of the HEMA-St block copolymers. Enhanced platelet movements on the HEMA-St block copolymer surface show that the microdomain surface interacts uniquely with platelets to hinder activation and preserve passive platelet function despite surface contact.

Adenosine Triphosphate↗

PubMed1998

Apoptosis and PCNA expression induced by prolactin in structural involution of the rat corpus luteum.

There are two stages of luteal regression. The first stage is functional regression that is characterized by a decreased production of progesterone secretion; the second stage of structural involution is referred to as a structural luteolysis. In rodents, prolactin has a biphasic action on the corpus luteum. It is luteotrophic, but when exposed to functionally regressed corpora lutea it causes luteolysis. The objective of the present studies was to examine mechanisms of prolactin action in structural luteolysis, whether apoptosis is involved in this process, and to examine the possible association of cell proliferation signals as mediators of structural luteolysis. Prolactin-induced structural luteolysis was associated with apoptosis verified by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL). Apoptotic cells made up about 3% of the cells 24 hours after the first injection of prolactin, a level that remained constant at all stages of structural luteolysis. Total ovarian weight and DNA content were decreased about 50% in 72 hours after induction of structural luteolysis by prolactin, The finding of about 3% of cells in apoptosis indicates apoptosis is a rapid process. Proliferating cell nuclear antigens (PCNA) of luteal cells were significantly decreased during functional luteal regression, but were conversely increased in structural luteolysis as shown by western blotting and immunohistochemistry. In general PCNA expression is reported to be decreased during structural involution, and there are no reports that have linked excess expression of PCNA with apoptosis and structural luteolysis. We speculate that an excessive increase in expression of PCNA which signals activation of cell proliferation creates a disorder in the signals involved with DNA synthesis. This disorder results in mitotic catastrophe and in the induction of apoptosis. Therefore the disorder of cell cycle signals in luteal cells are associated with prolactin induced apoptosis in structural luteolysis.

Animals↗

PubMed1998

Extensive intra-alveolar haemorrhage caused by disseminated strongyloidiasis.

We describe here four cases of disseminated strongyloidiasis. In Okinawa, it has been reported that about 10% of the residents are infected with Strongyloides stercoralis, but disseminated cases are rare. Detailed histopathological examination revealed that the present four cases could clearly be separated into two groups, two acute cases and two subacute cases. The acute cases died rapidly due to extensive diffuse intra-alveolar haemorrhage in both lungs. However, there were no inflammatory infiltrates, abscesses or granulomas in the lungs. Worms were demonstrated in the alveolar spaces. No extensive bleeding was observed in any organs except the lungs. The acute cases could be diagnosed as severe diffuse intra-alveolar haemorrhage syndrome, but deposition of immune complex (parasite antigen and immunoglobulins) and complement C3c was not demonstrated in the alveolar wall and small vessels of the lung. The subacute cases exhibited no such extensive haemorrhage, but scattered microabscesses were found with sepsis. During the migration of the worms from the colon, enteric bacteria entered the circulation in the two subacute cases. The acute cases received steroid therapy before the dissemination of the worms, but the two subacute cases did not. Steroids might have influenced the Strongyloides stercoralis dissemination and/or the course of the disease.

Adult↗

PubMed1998

Morphological observations of diarrhea in mice caused by aplysiatoxin, the causative agent of the red alga Gracilaria coronopifolia poisoning in Hawaii.

Diarrhea caused by the red alga Gracilaria coronopifolia poisoning was investigated in mice. The target site of a lethal dose was the whole small intestine where the toxin caused bleeding, resulting in hemorrhagic shock. With a sublethal dose, diarrhea appeared about 4.5 h after i.p. injection and continued for about 4 h intermittently. The site of diarrhea was the large intestine, where the submucosa first accumulated fluid from edema. Then the fluid moved into the lamina propria, the surface epithelial cells were broken and the fluid flowed into the lumen. Finally, diarrheic components apparently originating from capillaries were secreted directly into the lumen. The cecum was the main target of the diarrhea. After the diarrhea ended, the number of goblet cells was increased remarkably and many fine cracks were left on the surface of the epithelium.

Administration, Oral↗