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Biomedical subjects

A Kato

Publications and source records attributed to A Kato.

At least 109 records · Page 6Linked to original sources
PubMed2000

Selective potassium ion recognition by benzo-15-crown-5 fluoroionophore/gamma-cyclodextrin complex sensors in water.

Three fluoroionophores Cn (n = 1, 3, 5), in which the crown ether unit and pyrenyl moiety are connected by a -(CH2)n- spacer, have been used to construct supramolecular Cn/gamma-cyclodextrin (gamma-CyD) complexes for alkali metal ion sensing in water. The Cn (n = 3, 5) are found to selectively form 2:1 complexes with K+ in the presence of gamma-CyD and exhibit the pyrene dimer emission in water. Equilibrium analysis of the C3/gamma-CyD complex reveals that the observed dimer emission arises from a 2:1:1 complex of C3 with K+ and gamma-CyD. In the absence of K+, the fluorescence lifetimes for the dimer species ((C3)2CyD and (C3)2(CyD)2) and the monomer species (C3CyD and C3(CyD)2) are 13-18 and 130-180 ns, respectively. Upon addition of 0.10 M KCI, a rising component corresponding to pyrene excimer formation is observed at the dimer emission region. For the C3/gamma-CyD complex, the apparent association constant for K+ of (3.8 +/- 1.3) x 10(9) M(-2) is only slightly affected by the presence of Na+. Although the C5/gamma-CyD complex shows high sensitivity for K+, the selectivity for K+ over Na+ is lower than that of the C3/gamma-CyD complex. In contrast, fluoroionophore C1 with the shortest methylene spacer exhibits no response for alkali metal cations in the presence of gamma-CyD. These results demonstrate that the response function of supramolecular Cn/gamma-CyD complexes is strongly affected by the methylene spacer length of Cn. The highest K+ selectivity is obtained for the C3/gamma-CyD complexes in water.

Journal Article↗
PubMed2000

Mechanism of dibucaine-induced apoptosis in promyelocytic leukemia cells (HL-60).

Dibucaine, a local anesthetic, inhibited the growth of promyelocytic leukemia cells (HL-60) without inducing arrest of the cell cycle and differentiation to granulocytes. Typical DNA fragmentation and DNA ladder formation were induced in a concentration- and time-dependent manner. The half-maximal concentration of dibucaine required to induce apoptosis was 100 microM. These effects were prevented completely by the pan-caspase inhibitor z-Val-Ala-Asp-(OMe)-fluoromethylketone (z-VAD-fmk), thereby implicating the cysteine aspartase (caspase) cascade in the process. Dibucaine activated various caspases, such as caspase-3, -6, -8, and -9 (-like) activities, but not caspase-1 (-like) activity, and induced mitochondrial membrane depolarization and the release of cytochrome c (Cyt.c) from mitochondria into the cytosol. Processing of pro-caspase-3, -8, and -9 by dibucaine was confirmed by western blot analysis. Bid, a death agonist member of the Bcl-2 family, was processed by caspases following exposure of cells to dibucaine. However, 100 microM dibucaine scarcely inhibited oxidative phosphorylation, but it induced membrane permeability transition in isolated rat liver mitochondria. Taken together, these data suggest that dibucaine induced apoptosis of HL-60 cells through activation of the caspase cascade in conjunction with Cyt.c release induced by a processed product of Bid and depolarization of the mitochondrial membrane potential.

Anesthetics, Local↗
PubMed2000

Enthalpic destabilization of glycosylated lysozymes constructed by genetic modification.

To understand the role of polyglycosylation in protein stability, the thermodynamic changes in the denaturation of various polymannosyl lysozyme mutants (R21T, G49N, R21T/G49N) constructed by genetic modification were analyzed using differential scanning calorimetry (DSC). The denaturation temperature and the enthalpy change for unfolding of the lysozymes were reduced with an increase in the length of the polymannose chain and the number of binding sites to a protein, although the polymannosyl lysozymes revealed apparent heat stability in that no aggregation was observed and the enzymatic activity was conserved under conditions in which the wild-type lysozyme coagulated [S. Nakamura et al., J. Biol. Chem. 268 (1993) 12706-12712]. The reversibility of the denaturation of polymannosyl lysozymes was observed in the DSC curves obtained by reheating after heat denaturation, while it was not observed for the wild-type lysozyme. Based on these results, the polymannosyl lysozyme seems to easily refold due to the excellent reversibility of denaturation, despite the decreases in the enthalpic stabilization due to the strain in the protein molecule by the introduction of a polysaccharide chain.

Binding Sites↗
PubMed2000

Prostaglandins up-regulate vascular endothelial growth factor production through distinct pathways in differentiated U937 cells.

We previously reported that cyclooxygenase (COX)-2 was predominantly expressed in macrophages of human colonic adenomas (Int. J. Cancer 83, 470-475.). The role of prostaglandins (PGs) produced by COX-2-expressing macrophages in colon carcinogenesis is still unclear. Here we show that PGs up-regulate vascular endothelial growth factor (VEGF) production by activated macrophages through their specific receptors. mRNAs of both PGE-specific receptors and peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear receptor superfamily of ligand-dependent transcription factors, were expressed in phorbol 12-myristate 13-acetate-differentiated U937, a human macrophage model (H-Mac). Prostaglandin E(1) (PGE(1)) and 15-deoxy-Delta(12,14)-PGJ(2) (a potent PPARgamma ligand, 15d-PGJ(2)) dramatically increased VEGF production. The combination of PGE(1) and 15d-PGJ(2) additively increased VEGF production. In addition, PGE(1) significantly increased cAMP formation, whereas 15d-PGJ(2) did not affect cAMP formation. The effect of the combination of PGE(1) and 15d-PGJ(2) on cAMP formation was similar to that of PGE(1) alone. Unexpectedly, 15d-PGJ(2) also drastically increased IL-1beta production, an indicator of macrophage activation, although PGE(1) only mildly increased it. Additional enhancement of IL-1beta production was observed in the combination of PGE(1) and 15d-PGJ(2). These results suggest that PGs dramatically increased VEGF production by activated macrophages through specific PGE receptor and PPARgamma-mediated processes and that PGs may thereby promote tumor growth through VEGF production.

Alprostadil↗
PubMed2000

Interaction of Vesl-1L/Homer 1c with syntaxin 13.

Vesl-1S/Homer 1a, reported originally as Vesl/Homer, was isolated as a synaptic plasticity-regulated gene. The expression of Vesl-1S/Homer 1a is regulated during long-term potentiation in the hippocampus. Vesl-1L/Homer 1c, which appears to be formed by a splicing event, shares the N-terminus with Vesl-1S/Homer 1a and also contains additional amino acids at the C-terminus. The short form and the long form of the family members both interact with group 1 metabotropic glutamate receptors (mGluRs). We herein report the identification of syntaxin 13 as a molecule that interacts with Vesl-1L using yeast two-hybrid screening. Syntaxin 13 is a member of the syntaxin family and is regarded as soluble N-ethylmaleimide-sensitive attachment proteins receptors (SNAREs) in the endosomal membranes. The interaction of Vesl-1L and syntaxin 13 was biochemically confirmed by in vitro binding assays. The coexpression of the two proteins in the transfected cells resulted in a colocalization in the intracellular vesicle-like structures. We thus propose that the association of Vesl-1L with syntaxin 13 plays a role in the translocation of Vesl-1L to the intracellular organelles.

Amino Acid Sequence↗
PubMed2000

Induction of aquaporin-4 water channel mRNA after focal cerebral ischemia in rat.

Aquaporin-4 (AQP4) is a member of a water-selective channel aquaporin-family and mainly expressed in the several structures of the brain and in the collecting duct of the kidney. Here we show its functional involvement in the water homeostasis of the ischemic brain. The expression of AQP4-mRNA is increased in the peri-infarcted cortex during the observation period ( approximately 7 days) after MCA-occlusion, maximally on day 3. The change corresponds to the generation and resolution of brain edema monitored by MRI. The signals for the mRNA are predominantly observed in glial cells in the molecular and outer granular layer of the peri-infarcted cortex. These results indicate that AQP4 plays a role in post-ischemic edema formation.

Animals↗
PubMed2000

Neuronal activity in female rat preoptic area associated with sexually motivated behavior.

Single unit activities were recorded from 31 neurons in the preoptic area (POA) of female rats engaging in sexual interactions. Concurrent videotape recordings were used to establish a relationship between neuronal activity and particular behavioral events. In 14 of the 31 neurons, the firing rate changed in association with bouts of sexual activity. The remaining 17 fired with more variability regardless of episodes of sexual interactions. Peri-event histograms identified four types of neurons: type 1 (n=4) increased their firing rate when the female rats initiated proceptive behavior; type 2 (n=4) showed a brief activation when the male mounted; type 3 (n=4) fired in response to intromission, and type 4 (n=2) were inhibited prior to and throughout the display of lordosis reflex. Type 1 neurons fired at significantly higher rates during the solicitatory period, from the initiation of solicitatory locomotion to the male mounts. Their activity was suppressed when the males mounted successfully with intromission. Types 1-3 neurons were recorded from the transitional region between the medial and lateral POAs. Type 4 neurons were located more medially in the medial POA. Systemic injection of pimozide, a dopamine receptor blocker, diminished firing in type 1 neurons and abolished proceptivity. The firing pattern in type 1 neurons appeared to embody the motivational state of the animal with an implication for a consummatory value of penile intromission. Visceral or somatosensory inputs may be responsible for short bursts in types 2 and 3 neurons. Type 4 neurons behaved exactly as if they inhibit the execution of the lordosis reflex. The results showed separate sets of POA neurons each specifically associated with proceptive and receptive components of female rat sexual behavior.

Action Potentials↗
PubMed2000

Isolation and characterization of copia-type retrotransposons in Arabidopsis thaliana.

We isolated two copia-type retrotransposons from Arabidopsis thaliana. We named these elements AtRE1 (Arabidopsis thaliana Retro Element 1) and AtRE2. Nucleotide sequence analysis revealed that both elements have long terminal repeats (LTRs), and that their internal sequences include one large open reading frame that could encode Gag protein, protease, integrase, reverse transcriptase, and RNaseH. The deduced amino acids sequences contain several domains that are conserved among a large family of retrotransposons. The primer binding site for first-strand DNA synthesis and the polypurine tract for second-strand DNA synthesis existed at corresponding positions. A 5bp target site duplication (TSD) sequence was also found in the flanking region of LTRs. Southern hybridization and sequence determination of the flanking region demonstrated that AtREs exist at different loci in the two A. thaliana ecotypes Columbia and Landsberg erecta. Moreover, AtRE2 exists at two loci in Landsberg erecta, in contrast to the existence of only one copy in Columbia. These findings suggest that AtREs were recently transfected via some mediators or that AtREs were transposed after differentiation of the two ecotypes. One cDNA clone derived from the transcripts of AtRE1 was isolated, and the nucleotide sequence showed that this RNA was transcribed in the antisense direction. RT-PCR analysis revealed that AtRE1 was transcribed in both directions. This result suggests that the antisense RNA controls the expression of AtRE1 at the post-transcriptional level.

Amino Acid Sequence↗
PubMed2000

Complete nucleotide sequence of a plant tumor-inducing Ti plasmid.

Crown gall tumor disease in dicot plants is caused by Agrobacterium tumefaciens harboring a giant tumor-inducing (Ti) plasmid. Here, for the first time among agrobacterial plasmids, the nucleotide sequence of a typical nopaline-type Ti plasmid (pTi-SAKURA) was determined completely. In total, 195 open reading frames (ORFs) were estimated in the 206479 bp long sequence. 20 genes for conjugation, three for replication, 22 for pathogenesis and 37 for genetic colonization of host plants were found within two-thirds of the plasmid. These genes formed seven functional gene clusters with narrow inter-cluster spaces. In the remaining one-third of the plasmid, novel genes including homologs of mutT, Rhizobium nodQ and Sphingomonas ligE genes were found, which are likely to be responsible for the broad host range. Restriction fragment length variation indicates extreme plasticity of the part required for conjugational gene transfer and the above-mentioned one-third of the plasmid, even among closely related Ti plasmids.

Agrobacterium tumefaciens↗
PubMed2000

Co-distribution patterns of chromogranin B-like immunoreactivity with chromogranin A and secretoneurin within the human brainstem.

As members of the chromogranin family, chromogranin A, chromogranin B, and secretogranin II are acidic proteins found in large, dense core vesicles. They are endoproteolytically processed to smaller peptides and released after neuronal stimulation. Using immunocytochemistry, this study closely examines chromogranin B-like immunoreactivity within the human brainstem and then takes a comparative view of co-distribution patterns by chromogranin B, chromogranin A, and secretogranin II. We used an antiserum raised against a synthetic peptide (PE-11) present in the chromogranin B molecule. Secretogranin II was localized with an antiserum against secretoneurin, a 33 amino acid peptide, found within the secretogranin II precursor. Like chromogranin A and secretoneurin, chromogranin B is expressed through all levels of the human brainstem. Chromogranin B was exclusively detected in neuronal structures. The medial part of the substantia nigra pars reticulata, the nucleus interpeduncularis, the area of the central gray, and the raphe complex displayed a high density of PE-11-like immunoreactivity. Furthermore, a prominent staining was found in the medial, dorsal and gelatinous subnuclei of the solitary tract and the dorsal motor nucleus of vagus. The substantia gelatinosa of the caudal trigeminal nucleus and spinal cord were also very strongly PE-11-immunopositive. In conclusion, chromogranin B and secretogranin II showed similar distributions while neuronal localization typically differed from chromogranin A aside from a few exceptions. These findings may provide a framework for future research in revealing a functional role of chromogranin peptides in the human brainstem.

Adult↗
PubMed2000

Antibodies to molluscum contagiosum virus in the general population and susceptible patients.

BACKGROUND: Since many attempts to cultivate molluscum contagiosum virus (MCV) in vitro have been unsuccessful, it is difficult to prepare a large quantity of antigens. To assess the seroprevalence of antibodies against MCV in 508 subjects with or without clinical MCV infection, a truncated recombinant protein from open-reading frame MC133L was synthesized using Sendai virus expression system and applied to enzyme-linked immunosorbent assay as an antigen. OBSERVATIONS: Antibodies to MCV were present in 7 (58%) of 12 patients with molluscum contagiosum, 7 (6%) of 108 healthy controls, 7 (9%) of 76 with atopic dermatitis, and 7 (18%) of 39 patients with systemic lupus erythematosus, although no clinical MCV infection was observed in the latter 3 groups. Of 7 human immunodeficiency virus (HIV)-positive patients with molluscum contagiosum, 1 (14%) was antibody positive, compared with 5 (2%) of 266 HIV-positive patients without molluscum contagiosum. Serum samples from patients with atopic dermatitis and systemic lupus erythematosus showed a higher reactivity (P<.001) than those from healthy controls, while serum samples from HIV-positive subjects showed a lower reactivity (P<. 001). CONCLUSION: The humoral immune response to MCV is usually confined to patients with molluscum contagiosum and may be affected by the immunological condition of the host.

Adolescent↗
PubMed2000

A novel mutation that leads to a congenital factor XI deficiency in a Japanese family.

We have identified a novel mutation leading to a congenital deficiency of the coagulation factor XI (FXI) in a Japanese family. A propositus was a 42-year-old female patient without bleeding tendency. Coagulant activity and the antigen level of FXI in her plasma were below the detectable range. The nucleotide sequences of the FXI gene of this patient were determined by a direct sequence method established in this study. A novel nonsense mutation (CAA; Gly263 --> TAA; stop) was identified in exon 8 of the FXI gene. Her parents are first cousins, and a polymerase chain reaction-restriction-fragment length polymorphism analysis revealed that her parents were heterozygous at this nucleotide position. This patient inherited mutant alleles from her parents and is homozygous at this nucleotide position. The nonsense mutation in the FXI gene is responsible for her deficiency of FXI.

Adult↗
PubMed2000

Multi-functional biopolymer prepared by covalent attachment of galactomannan to egg-white proteins through naturally occurring Maillard reaction.

Protein-polysaccharide conjugate was prepared as a functional biopolymer using protein and polysaccharide via a Maillard-type reaction. Ovalbumin and lysozyme were conjugated with galactomannan under controlled heating and humidity conditions. The antioxidant effect of ovalbumin and the antimicrobial activity of lysozyme were enhanced by the glycosylation. The emulsifying properties of the egg protein were also significantly improved by the modification. The increase in lipid affinity due to the conjugation resulted in the enhancement of the radical scavenging ability of ovalbumin. The effectiveness of lysozyme and its glycosylated derivative in restricting the activity of a Gram-negative pathogen, Edwardsiella tarda in fish was also investigated.

Animals↗
PubMed2000

Improvement in the yield of lipophilized lysozyme by the combination with Maillard-type glycosylation.

Hen egg white lysozyme was modified using the Maillard-type glycosylation method prior to the lipophilization with palmitic acid. The yield of lipophilized lysozyme significantly increased by the pre-glycosylation of the protein. The lipophilized lysozyme derivative was separated into two main fractions with different level of glycosylation. All fractions showed a strong antimicrobial activity against Gram-negative bacteria, Escherichia coli. The lipophilization of the lysozyme combined with glycosylation is a promising method for potential industrial applications of the lysozyme due to the enhanced antimicrobial activity and the improved yield.

Anti-Bacterial Agents↗
PubMed2000

Movement-related desynchronization of the cerebral cortex studied with spatially filtered magnetoencephalography.

Event-related desynchronization (ERD) within the alpha and beta bands on unilateral index finger extension and hand grasping was investigated on six normal volunteers with magnetoencephalography (MEG). A novel spatial filtering technique for imaging cortical source power, synthetic aperture magnetometry (SAM), was employed for the tomographic demonstration of ERD. SAM source image results were transformed into statistical parametric images. On the same hand grasping task, a functional MRI (fMRI) study was conducted on two subjects and compared with the ERD result. When the MEG data were analyzed with the fast Fourier transformation, power attenuation within the alpha and beta bands was evident on the contralateral sensorimotor area just prior to movement onset. The tomographic distribution of ERD was clearly obtained with SAM statistical imaging analysis. The equivalent current dipole (ECD) for the signal-averaged motor field was localized to the hemisphere contralateral to the hand movement, roughly at the center of the region displaying beta-band ERD. The signal increase on fMRI roughly colocalized with the ERD on the contralateral sensorimotor area. In conclusion, with the novel spatial filtering technique for the brain magnetic field, SAM, cortical regions contributing to ERD on finger movement were successfully demonstrated in a tomographic manner. The relative colocalization of the contralateral SAM ERD with ECD as well as the fMRI activation suggests that SAM is a practically useful technique to extract event-related signals from brain noise.

Adult↗
PubMed2000

Whole-genome analysis of human astrocytic tumors by comparative genomic hybridization.

Frozen sections of 35 astrocytic tumors of various histologic malignancies were analyzed by comparative genomic hybridization in an attempt to characterize the profile of genetic aberrations. Over 94% of the samples revealed DNA copy number aberrations, which increased with higher histological malignancy grades, and also involvement of more than one chromosome was seen in 85% of instances. The aberrations observed were mainly deletions and most frequently incorporated chromosomes 1p, 10, 19q, and 22q. On the other hand, gains or amplifications were detected only in glioblastomas. Additionally, such gains or amplifications were present in all tumor samples where the initial histopathological diagnosis was glioblastoma and immunohistochemical study disclosed p53 tumor suppressor protein negative and epidermal growth factor receptor positive immunoreactivity; such glioblastomas possessing p53 tumor suppressor protein positive and epidermal growth factor receptor negative immunoreactivity seldom displayed any gain. Thus, glioblastomas exhibiting two different profiles of genetic aberrations were recognized--one with and the other without any gains/ amplifications. We speculate that the former variety is de novo glioblastoma.

Adult↗