Biomedical subjects

T Ueki

Publications and source records attributed to T Ueki.

At least 109 records · Page 6Linked to original sources

PubMed1995

Screening and production of arylsulfatases for target therapy with etoposide 4'-sulfate, an antitumor prodrug.

Two arylsulfatase-producing streptomycetes that desulfated etoposide 4'-sulfate were isolated from soil samples. Taxonomical study identified one soil isolate as Streptomyces griseorubiginosus S980-14 (Es-1 arylsulfatase producer), while the other was considered new and tentatively designated Streptomyces sp. T109-3 (Es-2 arylsulfatase producer). Both strains produced extracellular arylsulfatase activities, provided that cultivation media were prepared with distilled water. Unlike the two known types of arylsulfatases, which had significant activity on p-nitrophenyl sulfate but none on etoposide 4'-sulfate, the crude streptomycete arylsulfatases efficiently desulfated etoposide 4'-sulfate and p-nitrophenyl sulfate, which supports the establishment of a new type of arylsulfatases.

Antineoplastic Agents↗

PubMed1995

Arylsulfatase from Streptomyces griseorubiginosus S980-14.

A new arylsulfatase designated Es-1, which desulfated etoposide 4'-sulfate and p-nitrophenyl sulfate, was isolated from Streptomyces griseorubiginosus S980-14 and purified to protein homogeneity by ammonium sulfate fractionation, ion exchange column chromatography, and chromatofocusing. The enzyme was active in monomeric form with an approximate molecular weight of 45,000, had a pI value of 4.95, and required calcium for full activity. At an optimum reaction pH of 8.5, iodoacetate, mercurous chloride, and EDTA severely inhibited the activity of Es-1 arylsulfatase.

Arylsulfatases↗

PubMed1995

A new type of Streptomycete arylsulfatase with high affinity to the sulfuryl moiety of the substrate.

Streptomyces sp. T109-3 arylsulfatase (Es-2), which desulfated p-nitrophenyl sulfate as well as etoposide 4'-sulfate, was purified to protein homogeneity by sulfated cellulose affinity and DEAE-cellulose column chromatographies. Es-2 required calcium for enzyme activity and was severely inhibited by SH and chelating reagents. Comparative characterization showed that, although distinct in recognition of the binding moiety of substrate, Es-1 (Streptomyces griseorubiginosus S980-14 arylsulfatase) and Es-2 shared high desulfating activity on etoposide 4'-sulfate and many other common enzymological characteristics, which suggested they would be acceptable as the enzyme component of antitumor antibody-enzyme conjugates for target chemotherapy.

Amino Acid Sequence↗

PubMed1995

Expression of ICAM-I on M cells covering isolated lymphoid follicles of the human colon.

To clarify the immunological function of 'M' (microfold or membranous) cells in the large intestine, we examined the expression of intercellular adhesion molecule-1 (ICAM-1) and HLA-class II antigens immunohistochemically in M cells and follicle-associated epithelia (FAE) covering isolated lymphoid follicles of the human colon in comparison with their expression in Peyer's patches of the small intestine. In Peyer's patches of the small intestine, ICAM-1 was not expressed on the epithelial cells covering the lymphoid follicles, but their cell surfaces were stained positively for HLA-DR. In contrast, colonic M cells expressed ICAM-1 on their cell surfaces but were negative for HLA class II antigens. By immunoelectron microscopy, ICAM-1 was seen to be distributed on the surface of microfolds, on the membranes of apical vesicles and on part of the basolateral plasma membranes of M cells, but was not expressed on adjacent FAE. These findings imply that the M cells in the colon and in Peyer's patches have different immunological roles. In addition, identification of ICAM-1 expression on the colonic M cells should help elucidate the pathogenesis of some inflammatory colonic diseases which appear to start in the lymphoid follicles of the colonic mucosa.

Adult↗

PubMed1995

Susceptibility for hydroperoxide formation of phosphatidylcholine and phosphatidylethanolamine in liposomes.

To compare the peroxidative susceptibilities of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in liposomes, multilamellar vesicles (MLVs) were prepared with equimolar L-alpha-dilinoleoyl PC (DLPC) and L-alpha-dilinoleoyl PE (DLPE), and with soya PC and soya PE having a uniform constituent fatty acids. The hydroperoxide formation at 37 degrees C in the presence of a water-soluble radical initiator was examined by chemiluminescence-high-performance liquid chromatography (CL-HPLC), and the effect of heterogeneous distribution of PC and PE on peroxidation was investigated. No difference was found between the hydroperoxidation of PC and PE in MLVs systems, except that soya PC was more susceptible to peroxidation than soya PE in the L-alpha-dipalmitoyl PC (DPPC)-based liposomes. No correlation was found between the amount of phospholipids distributed in the external leaflet of MLVs and hydroperoxide formation. This result suggested that the unsaturation of constituent fatty acids in phospholipids is more important than the difference in the polar head group of phospholipids regarding their peroxidizabilities in liposomes.

Chromatography, High Pressure Liquid↗

PubMed1995

[Analysis of factors related to the recent decline in birth rate in Japan].

This study was undertaken in an attempt to determine whether regional differences exist for those factors which have affected the decline in the total fertility rate in Japan between 1970 and 1990. Age Stratified analysis of vital statistics of the 20 to 39-year-old female population for the 46 prefectures was performed, and evaluated in relation to urbanization. The parameters examined were birth rate, percentage of married women, rates of birth by married women, and percentage of the work force in the service industry. The results were as follows. 1. Characteristic changes were noted in birth rates for females between 25 and 29 years of age. The reasons are that average marriage age for females shifted from 20-24 to 25-29, causing the birth rates for females between the ages of 25 to 29 years to decline, while not uniformly, but with some regional differences among the 46 prefectures. 2. Urbanization has had a significant effect on the declining birth rate for females grouped by age. The advance of the urbanization process in each prefecture is directly related to the decline in the birth rates for females between 20 to 24 years and 25 to 29 years. The extent of urbanization in each prefecture is inversely related to the rate of birth by married women and the percentage of married women between age 20 to 24 and 25 to 29 in that prefecture. The trend toward delaying marriage and childbirth in the urbanized prefectures appeared to be a major factor leading to the decline in the total fertility rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1994

Astrocytic contribution to functioning synapse formation estimated by spontaneous neuronal intracellular Ca2+ oscillations.

Glial contribution to in vitro synaptic function was investigated in a neuron-glia co-culture system by monitoring spontaneous oscillations of intracellular Ca2+ in neurons. Rat cortical neurons, grown stably on a cortical astrocyte monolayer, extended neurites resulting in marked functional synapse formation. Little synapse formation was observed in neuronal co-culture with meningeal fibroblasts or endothelial cells. Aged astrocytes in vitro (C35) were found to attenuate synaptic development, while young astrocytes (C5) markedly promoted synaptic function. C5 and C35 astrocyte media conditioned yielded no significant synaptogenic effect, indicating diffusible factor(s) are not responsible for our observation. Modulation of astrocytic proliferation and differentiation by gliostatin, a glial growth inhibitor, or dibutyryl cAMP affected neuronal synaptic function on the co-cultures. Site-specific analysis in homologous and heterologous neuron-astrocyte co-cultures among cortex, hippocampus, septum, and striatum revealed that homologous combinations of neurons and astrocytes derived from identical brain regions elicited the largest number of synchronizing neurons. These results suggest that in vivo neuronal synaptic function essentially requires the participation of adjacent astrocytes, which is site-specific and age-dependent.

Animals↗

PubMed1994

Expression on outer membranes of mannose residues, which are involved in osteoclast formation via cellular fusion events.

Osteoclast, the bone-resorbing cell, is formed from hematopoietic precursors via cell-cell fusion. To evaluate the possibility that under certain specific conditions mannose residues may be expressed on the mammalian cell surface, we examined the action of pradimicin derivatives, which bind specific sugars such as the mannose residue, on the formation of osteoclast induced in the coculture of mouse spleen cells with mouse stromal cells, a process in which cell-cell fusion is involved. Osteoclast formation was inhibited by treatment of this coculture system with pradimicin at the later stage (day 4-7), and this inhibition was specifically abrogated by mannose-rich yeast mannan. During the 8-day cocultivation, osteoclast formation was blocked by the pradimicin on days 6 and 7, when mononuclear preosteoclasts fused into multinucleated osteoclasts. With an interactive laser cytometer ACAS570, fluorescein isothiocyanate-labeled pradimicin was observed to bind osteoclast progenitors at the fusion stage and to have no binding affinity for osteoclast progenitors at the early stage (day 0-3) or for osteoclasts, which were formed after performing fusion between mononuclear preosteoclasts. These results suggest that mannose residues were expressed on outer membranes of monocytes under pathophysiological conditions and that they were involved in the osteoclast formation via cellular membrane fusion events.

Animals↗

PubMed1994

Significance of amino groups of phosphatidylethanolamine in phospholipid peroxidation of mixed liposomes.

The effect of distribution of phosphatidylethanolamine (PE) in multilamellar vesicles (MLV) on their peroxidative susceptibility was studied. Liposomes containing various ratios of L-alpha-dilinoleoyl phosphatidylcholine (DiLinPC) and L-alpha-dilinoleoyl phosphatidylethanolamine (DiLinPE) were peroxidized by ferrous ion or a water-soluble radical initiator 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH). The oxygen consumption rate was compared with the formation kinetics of fluorescent products. Inclusion of PE in liposomes was found to accelerate the Fe(2+)-dependent peroxidation. Modification of the amino group of PE with 2,4,6-trinitrobenzenesulfonic acid (TNBS) inhibited Fe(2+)-induced oxygen consumption in the late stage where fluorescent substances formed. A possible role of the amino group of PE on lipid peroxidation is discussed, especially in terms of its reactivity with oxidation products and subsequent formation of fluorescent substances.

Amidines↗

PubMed1994

Human neuroblastoma growth inhibitory factor (h-NGIF), derived from human astrocytoma conditioned medium, has neurotrophic properties.

Investigations on the general characteristics of human astrocytoma cell line NAC-1 revealed neuroblastoma growth inhibitory activity in conditioned medium. Neuroblastoma growth inhibitory factor (NGIF) was partially purified by Econo Q, Econo CM, and Superose 12 column chromatography. The protein is weakly basic with an estimated M(r) of 120,000, possibly having an M(r) 60,000 dimeric structure. NGIF inhibits the growth of human neuroblastoma cell lines but has no effect on morphology nor does it produce any change in the growth of human glioblastoma cell lines. Interestingly, NGIF appears to promote survival and neurite outgrowth of embryonal rat cortical neurons. These neurotrophic properties suggest a role for NGIF in the development of the nervous system.

Animals↗

PubMed1994

Epstein-Barr virus in gastric carcinoma with lymphoid stroma. Special reference to its detection by the polymerase chain reaction and in situ hybridization in 99 tumors, including a morphologic analysis.

BACKGROUND: Gastric carcinoma with lymphoid stroma (GCLS) has been reported to have a more favorable prognosis than ordinary gastric carcinoma, however, the precise mechanism of the pathogenesis for GCLS remains unclear. METHODS: The authors analyzed 99 GCLS in 94 patients for Epstein-Barr virus (EBV) sequences using polymerase chain reaction (PCR) and in situ hybridization (ISH); these were compared with 42 ordinary gastric carcinomas. RESULTS: Two series of PCR showed 81 (82%) and 46 (47%) of the 99 GCLS to have EBV sequences, which were significantly higher compared with ordinary gastric carcinoma (50% and 9.5%, respectively). With ISH using thymine-thymine dimerized oligonucleotide probes corresponding to EBV-encoded small RNA 1 (EBER1), 82 (83%) of 99 GCLS showed clear, intense hybridization signals localized over the nuclei of the tumor cells, in contrast to only 4 (9.5%) of 42 ordinary carcinomas (P < 0.001). A comparative morphologic analysis of EBER1-positive and negative GCLS revealed that typical features of GCLS, such as mild cellular pleomorphism, rare mitoses, a marked degree of lymphoid stroma, and mild fibrosis, together with a lymphoid infiltration within the cancer cell nests were significantly more frequent in EBER1-positive GCLS. CONCLUSIONS: More than 80% of GCLS were associated with EBV. The presence of EBV association in GCLS was characterized by the above morphologic features.

Adenocarcinoma↗

PubMed1994

Polyhedral assembly of a membrane protein in its three-dimensional crystal.

A novel ordered assemblage of bacteriorhodopsin, a transmembrane protein functioning as a light-driven proton pump, is found in its three-dimensional crystal. Atomic force microscope images of the crystal surface reveal that spherical protein clusters with a diameter of approximately 50 nm are hexagonally close-packed. Electron micrographs of mechanically disintegrated crystals show that the inside of the protein cluster is filled with the mother liquor. The crystal is made up of hollow protein clusters. When disintegrated crystals are illuminated in the presence of a lipophilic anion, a significant alkalization of the external medium occurs. This result indicates that the protein cluster contains native lipids and that the cytoplasmic side of the protein faces the external medium. X-ray diffraction patterns and the observed diameter of the spherical shell suggest that approximately 200 bacteriorhodopsin trimers are aligned on a polyhedral surface lattice. Another remarkable feature of the spherical assemblies of bacteriorhodopsin is that they fuse with each other at low ionic strength and occasionally form a tubular or doughnut-like structure. The concept of membrane protein polymorphism is introduced on the basis of these observations, and it is used to describe the dynamic structure of some other biological membranes.

Bacteriorhodopsins↗

PubMed1994

Autonomy of expression of epidermis-specific genes in the ascidian embryo.

An example of developmental autonomy, assessed at the level of expression of tissue-specific genes, was characterized in this study. cDNA clones that corresponded to two different epidermis-specific genes (HrEpiA and HrEpiB) of the ascidian Halocynthia roretzi were isolated. Transcripts of both genes first appeared around the time of gastrulation, suggesting zygotic expression. In the case of HrEpiA, transcripts became undetectable after metamorphosis had begun, while transcripts of HrEpiB were still detectable in juveniles after metamorphosis. In situ hybridization analysis using HrEpiA and B probes gave the following results. (1) All types of partial embryo that originated from blastomeres with epidermal fate from two-, four-, and eight-cell embryos expressed these two epidermis-specific genes. (2) When cleavage was blocked by treatment with cytochalasin B at the one-cell stage, the cleavage-arrested one-celled embryos expressed the two genes. (3) Even when blastomeres with epidermal fate were isolated from two-, four-, and eight-cell embryos and the division of the blastomeres was arrested immediately after isolation, they expressed the two specific genes. These results suggest that the epidermal lineage in the early ascidian embryo is a developmental system with considerable self-sustainability.

Amino Acid Sequence↗

PubMed1994

An ascidian homolog of SEC61 is expressed predominantly in epidermal cells of the embryo.

In eukaryotic cells, SEC61 protein is essential for protein translocation across the endoplasmic reticulum membrane. Because of the ubiquitous nature of the protein, the expression of the corresponding gene(s) during embryogenesis has not received much attention. We found that an ascidian homolog of SEC61 is expressed predominantly in embryonic epidermal cells. A cDNA clone for Halocynthia roretzi SEC61 (HRSEC61) gene contains a single open reading frame that encodes a polypeptide of 475 amino acids. The degree of amino-acid identity was 87% between the ascidian and the dog and 55% between the ascidian and yeast. The HRSEC61 gene was transcribed maternally and zygotically. A low level of the corresponding mRNAs, about 2.3 kb in length, was found in eggs and early embryos. Zygotic mRNAs appeared after the gastrula stage, and the accumulation of the mRNAs was maximal at the neurula and tailbud stages. In situ hybridization of whole-mount specimens demonstrated that, although maternal mRNAs were distributed evenly in eggs and early embryos, the occurrence of zygotic mRNAs was predominant in differentiating epidermal cells. The predominant expression of HRSEC61 in embryonic epidermal cells was determined using cleavage-arrested embryos; those at the 16- or 32-cell stage expressed HRSEC61 in the presumptive epidermal cells of the animal hemisphere.

Amino Acid Sequence↗

PubMed1994

The hydration of Ras p21 in solution during GTP hydrolysis based on solution X-ray scattering profile.

The small-angle X-ray scattering technique was used to characterize the structure in solution of wild type ras p21 as well as the oncogenic proteins mutated at residue 12, 59, or 61. In the presence of GDP, the radius of gyration, Rg, determined for wild type ras p21 was 16.89 +/- 0.01 A, while the wild type ras p21 bound to the GTP analogue GDPNHP (5'-guanyl imido diphosphate beta-gamma-imidoguanosine 5'-triphosphate) showed an Rg value of 17.46 +/- 0.01 A, which is 3.3% larger. The result shows that ras p21 expands upon GTP binding. The Rgs of mutated proteins were 17.04 +/- 0.01, 16.98 +/- 0.01, and 17.03 +/- 0.01 A for the Gly-12 to Val, Ala-59 to Thr, and Gln-61 to Leu mutants, respectively. The scattering profiles were analyzed by simulation of hydrated ras p21, based on the crystal atomic coordinates, and it was concluded that the ras p21 molecule incorporates 20% more bulk water upon GTP binding. The increase of bulk water is especially conspicuous around the interface between switch I (residues 32-40) and switch II (residues 60-66) regions. This suggests that hydration plays an important role in the interaction with GAP.

Computer Simulation↗

PubMed1994

Distribution of complement regulatory proteins, decay-accelerating factor, CD59/homologous restriction factor 20 and membrane cofactor protein in human colorectal adenoma and cancer.

To clarify the events related to complement-mediated immune responses in human colorectal cancers, we immunohistochemically examined the distribution of decay-accelerating factor (DAF), CD59/homologous restriction factor 20 (HRF20), membrane cofactor protein (MCP) and terminal complement complex (TCC) in human colorectal adenomas and cancers, and then compared the findings with their distribution in normal colonic mucosa. In the normal mucosa, TCC was not present on epithelial cells. Whereas DAF and CD59/HRF20 were present only occasionally on the apical surfaces of normal epithelial cells, MCP was diffusely distributed on the basolateral surfaces of most epithelial cells of the colon. These findings suggest that MCP has a primary role in the regulation of complement activation on these cells. In adenoma cells, the expression of both DAF and CD59/HRF20 was enhanced. In cancer cells, the expression of CD59/HRF20 and MCP was diminished, whereas DAF expression was markedly enhanced. Since DAF was frequently stained in the lumen of the cancer glands, it was suggested that DAF was released into the colonic lumen in patients with colorectal cancer.

Adenoma↗

PubMed1993

Neurotrophic action of gliostatin on cocultured neurons with glial cells.

Gliostatin is a polypeptide factor (apparent M(r) = 100 k with a homodimeric structure comprising two 50 kDa subunits) acting on cortical neurons (neurotrophic action) as well as astrocytic cells (growth inhibition). Under the coculture system of cerebral cortical neurons and astrocytes from fetal rats (E15 or E16), the neurotrophic action of gliostatin was examined immunocytochemically. Immunostaining by an anti-neurofilament (NF) monoclonal antibody visualized a marked neurite-outgrowth and interconnecting bundles of neuritic processes induced by gliostatin in the coculture system. Neurons stimulated by gliostatin formed dense aggregates in clumps, while neurons in control coculture spread out. Gliostatin has also shown survival-promoting effects on neurons. Furthermore, it was shown that gliostatin induced the differentiation of protoplasmic astrocytes to fibrous astrocytes. These results further support our previous contention that gliostatin plays physiological roles on neuronal and glial development.

Animals↗

PubMed1993

Structural change of jack bean urease induced by addition of surfactants studied with synchrotron-radiation small-angle X-ray scattering.

Both the quaternary and subunit structures of jack bean urease in solutions with ionic and nonionic surfactants have been studied by small-angle X-ray scattering using a synchrotron-radiation source. The effects of those surfactants on the enzyme activity of urease have also been investigated in the same kind of solvent systems as those used for the scattering experiments. The present results show that the quaternary structure of urease in solution is fairly elongate and that by the relatively minor binding of SDS (SDS/protein = 0.23/1) the native urease molecule is dissociated into six identical subunits with nearly spherical structures. In addition the enzyme activity of urease was mostly retained under every solvent condition investigated, indicating that the subunit found in the present scattering experiments is the fundamental monomeric unit for both the quaternary-structure formation and enzyme function of urease.

Fabaceae↗