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Biomedical subjects

M Higuchi

Publications and source records attributed to M Higuchi.

At least 127 records · Page 7Linked to original sources
PubMed1996

[Tau protein in cerebrospinal fluid--a potential marker of Alzheimer's disease].

Levels of the microtubule-associated protein tau in cerebrospinal fluid (CSF-tau) were measured in samples from 87 patients with Alzheimer's disease (AD), 114 patients with non-AD neurological diseases, and 22 normal control subjects, by sandwich enzyme-linked immunosorbent assay. The CSF-tau level was significantly higher in patients with AD than in patients with non-AD neurological diseases and in controls. High CSF-tau levels were found irrespective of age at onset, apolipoprotein E genotype, clinical stage, and ethnic group. Western blots of AD CSF proteins revealed two to three immunoreactive bands with apparent molecular mass between 50 and 65 kDa, which is consistent with phosphorylated CSF-tau. These results suggest that CSF-tau reflects progressive accumulation of tau due to the progressive death of neurons in the AD brain. Assay of CSF-tau may prove to be a reliable diagnostic test for AD.

Aged↗
PubMed1996

[Combination therapy with irinotecan and CBDCA for patients in terminal stage of ovarian carcinoma].

Combination chemotherapy with irinotecan and CBDCA was performed for two patients in the terminal stage of ovarian carcinoma. Every week, 75 mg.m-2 of irinotecan and 75-100 mg.m-2 of CBD CA were intravenously administered. Both patients showed a partial response. Diarrhea was not a characteristic side effect of irinotecan in this case. Dose limiting factors were leucopenia and thrombocytopenia.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Protease inhibitors differentially regulate tumor necrosis factor-induced apoptosis, nuclear factor-kappa B activation, cytotoxicity, and differentiation.

We investigated the effect of various protease inhibitors on several tumor necrosis factor (TNF)-mediated cellular responses. Treatment of a human myelogenous leukemia cell line, ML-1a, with TNF in the presence of cycloheximide triggers endonucleolytic activity and apoptotic cell death within 90 minutes. The general serine protease inhibitor diisopropyl fluorophosphate (DFP) and the chymotrypsin-like protease inhibitor N-tosyl-L-lysyl chloromethyl ketone (TPCK) completely abrogated TNF-induced DNA fragmentation and the formation of apoptotic bodies. However, 13 other protease inhibitors, including serine protease inhibitors, did not. The addition of TPCK to cells 30 minutes after TNF treatment completely inhibited the cytokine action, indicating that TPCK-sensitive proteases are not involved in the early stages of signal transduction. TNF is cytotoxic and induces differentiation in ML-1a cells after a 3-day incubation. TPCK had no effect on the TNF-induced cytotoxicity and differentiation, indicating that TPCK-sensitive proteases are specific for DNA fragmentation. TPCK also blocked TNF-induced activation of nuclear factor (NF)-kappa B. The dose-response and the time-course of the inhibitor, however, indicated that the site of action of TPCK for NF-kappa B activation and for DNA fragmentation are quite distinct. Therefore, we conclude that TNF activates two distinct TPCK-sensitive pathways, one leading to apoptosis and the other to NF-kappa B activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Editing of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor GluR-B pre-mRNA in vitro reveals site-selective adenosine to inosine conversion.

In neurons of the mammalian brain primary transcripts of genes encoding subunits of glutamate receptor channels can undergo RNA editing, leading to altered properties of the transmitter-activated channel. Editing of these transcripts is a nuclear process that targets specific adenosines and requires a double-stranded RNA structure configured from complementary exonic and intronic sequences. We show here that the two independent editing sites in alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor GluR-B pre-mRNA are edited with positional accuracy by nuclear extract from HeLa cells. Nucleotide analysis by thin layer chromatography of the edited RNA sequences revealed selective adenosine to inosine conversion, most likely reflecting the participation of double-stranded RNA adenosine deaminase. Our results predict the presence of inosine-containing codons in other mammalian mRNAs.

Adenosine↗
PubMed1995

Attachment and growth of fibroblast cells on silk fibroin.

The attachment and growth of fibroblast cells (L-929) on matrices of silk fibroin from Bombyx mori domestic silkworm (DSF) and Antheraea pernyi wild silkworm (WSF) were studied by a cell culture method. The performance of the two kinds of silk fibroin was compared to that of collagen. DSF exhibited as high a cell attachment and growth as collagen did. The cells attached to DSF were extensively spread out and their filopodia were visible in the SEM pictures. WSF, which contains the tripeptide sequence Arg-Gly-Asp (believed to be a specific interaction site for cell-attachment), displayed much higher cell attachment and growth compared to DSF. The cells attached on WSF became virtually flat and their filopodia could be seen, indicating that the cells were very strongly held on the surface.

Amino Acid Sequence↗
PubMed1995

Characterization of the apoptotic effects of human tumor necrosis factor: development of highly rapid and specific bioassay for human tumor necrosis factor and lymphotoxin using human target cells.

Currently available bioassays for most cytokines require several days and therefore must be performed under sterile conditions. In this report we describe a bioassay for tumor necrosis factor (TNF) and lymphotoxin (LT) that is extremely rapid and specific and does not require sterile conditions. Using tritiated thymidine release, we could conveniently monitor degradation of DNA into small fragments following the incubation of human myelogenous leukemia ML-1a cells with TNF. The assay showed that TNF-dependent DNA fragmentation was potentiated by cycloheximide and occurred within 90 min. Treatment of cells to TNF lead to apoptosis as indicated by thymidine release, DNA laddering on agarose gels and morphological alterations. Under these conditions, plasma membrane were not damaged as indicated by lack of chromium release. This effect was linear with TNF concentration. This assay had high throughput, did not require sterile conditions, could be carried out in the absence of serum, and was sensitive only to TNF and LT and not to interferon (IFN)-alpha, IFN-beta, IFN-gamma, transforming growth factor beta, interleukin-4, leukemia inhibitory factor and granulocyte-monocyte colony stimulating factor; all cytokines known to inhibit different cell types. Besides detection of TNF in biological fluids, this assay may prove useful for the identification of novel inhibitors of TNF action.

Apoptosis↗
PubMed1995

Differences in the interleukin-2 (IL-2) receptor system in human and mouse: alpha chain is required for formation of the functional mouse IL-2 receptor.

Reconstitution with mouse interleukin-2 (IL-2) receptor subunits demonstrated that the mouse IL-2 receptor complex was different from the human complex in the alpha chain requirement for the functional mouse receptor complex. The heterotrimeric complex of the mouse exogenous alpha and beta chains and the endogenous gamma chain on mouse lymphoid BW5147 cells showed the ability to bind IL-2 with high affinity, resulting in IL-2-induced tyrosine phosphorylation of a cytosolic tyrosine kinase, JAK3, which is involved in IL-2-dependent signals. Exogenous introduction of the beta chain with the endogenous gamma chain, however, could neither confer appreciable IL-2 binding nor IL-2-induced signal transduction on BW5147 cells, unlike the human beta gamma heterodimer. Mouse spleen CD8+ cells, not having the alpha chain initially, showed IL-2-dependent cell proliferation only when expression of the alpha chain was induced. Collectively, these results illustrate that the functional mouse IL-2 receptor complex necessarily includes the alpha chain, and that the regulation of CD8+ T cell growth during immune reaction depends upon alpha chain expression.

Animals↗
PubMed1995

Transformation of type 1 astrocytes with N-ethyl-N-nitrosourea: establishment of an in vitro system and the role of the p53 gene.

N-ethyl-N-nitrosourea (ENU)-induced gliomas, animal models of human gliomas, are most frequently oligodendrocytic, while human gliomas tend to be astrocytic. To facilitate a detailed study of human glial carcinogenesis, we developed an in vitro system using type 1 astrocyte transformation with ENU. Type 1 astrocytes from fetal Wistar rat brain were treated by a single dose of ENU. Transformed colonies appeared 50 days after exposure to single doses of ENU greater than 150 micrograms/mL. Cloned cells from these colonies retained the immunohistochemical characteristics of type 1 astrocytes. They showed rapid growth and high saturation densities, colony formation in low (2%) serum medium and gave rise to tumors when injected into nude mice. When p53 expression was studied at each passage, a single cell positive for mutant p53 protein emerged 40 days after ENU treatment. In the next 1-3 passages, the mutant p53 positive cell formed piled-up colonies and exhibited dominant growth. Northern blot analysis showed markedly increased accumulations of p53 mRNA in transformed cells. This in vitro transformation system of type 1 astrocytes provides a valuable tool for further investigations of astrocyte carcinogenesis.

Animals↗
PubMed1995

Combined choriocarcinoma, hepatoid adenocarcinoma, small cell carcinoma and tubular adenocarcinoma in the oesophagus.

We describe an oesophageal tumour composed of choriocarcinoma, hepatoid adenocarcinoma, small cell carcinoma and tubular adenocarcinoma. The choriocarcinomatous areas and hepatoid adenocarcinomatous areas contained beta human chorionic gonadotropin-positive cells and alpha fetoprotein-positive cells, respectively. The small cell carcinomatous areas contained cells positive for serotonin or adrenocorticotrophic hormone, while the tubular adenocarcinomatous areas contained cells positive for carcinoembryonic antigen. Non-neoplastic gastric type columnar epithelium was found directly adjoing the tumour at the oral side. This tumour, with its unprecedented histology combination of tissues may have originated in Barrett's oesophagus, although we could not confirm a history of chronic gastro-oesophageal reflux.

Adenocarcinoma↗
PubMed1995

Differential expression of Notch1 and Notch2 in developing and adult mouse brain.

The Notch gene encodes a large transmembrane protein, and is required for the correct differentiation of both neural and non-neural tissues in Drosophila. Mammals have more than one Notch gene homolog, e.g. Notch1 and Notch2. Here, in order to determine the role of Notch genes in the mouse nervous system, we used in situ hybridization to study the expression of the Notch1 and -2 genes through mouse embryogenesis and into adulthood. The expression of Notch1 and Notch2 differed throughout development. Notch2 was expressed in the embryonic ventricular zone, the postnatal ependymal cells, and the choroid plexus throughout embryonic and postnatal development. Notch1 was also expressed in the ventricular zone between embryonic days 10 and 14, but its expression decreased gradually as embryos developed. The postnatal mouse brain strongly expressed Notch2, but not Notch1, in the granular cell layer of hippocampal dentate gyrus, where neurogenesis continues even in adult rodents. The most remarkable finding was the detection of a strong signal for Notch2 mRNA in two circumventricular organs: the subfornical organ and the area postrema. The receptor encoded by the Notch2 gene, which is located in these areas, may respond to unknown ligands in CSF. This putative receptor may participate in signal transduction by way of both neural and humoral links. These data suggest that Notch2, rather than Notch1, is related not only to development, but also to some postnatal functions of mouse central nervous system.

Animals↗
PubMed1995

Role of high glycogen in underperfused diabetic rat hearts with added norepinephrine.

The relationship between cardiac dysfunction and glycogen level and/or duration of diabetes was examined during underperfusion (2 ml/min/g heart weight) with 10(-6)M norepinephrine (NE) in isolated 1- and 6-week streptozotocin-diabetic rat (diabetes mellitus, DM) hearts and non-DM hearts. Glycogen levels in non-DM and 1- and 6-week DM hearts were 85, 120, and 206 mumol/g dry weight, respectively, in the subendocardium. About 13 min after the start of underperfusion with NE, the diastolic tension in 1-week DM hearts began to increase when the glycogen level had decreased to half; in 6-week DM hearts, glycogen decreased more markedly without greater lactate accumulation, but these glycogen levels were still higher (104 mumol/g dry weight) than those in 1-week DM hearts and the diastolic tension did not increase. About 17 min after the onset of underperfusion, the glycogen decreased to the 13-min level of 1-week DM hearts (64 mumol/g dry weight) and the diastolic tension began to increase. Until 20 min after the onset of underperfusion, the injury was less in 6-week than in 1-week DM hearts. However, after 60-min underperfusion with NE, when the glycogen level was markedly low in both groups ( < 20 mumol/g dry weight), diastolic tension was increased twice as much in 6-week DM as in 1-week DM hearts and was related to the decreased subendocardial ATP level. The results indicate that the markedly high glycogen content in diabetic hearts probably helps delay the start of the increase in left ventricular (LV) stiffness during underperfusion with NE. Ultimately, however, the degree of the injury depends on the duration, i.e., the severity, of the diabetes.

Adenosine Triphosphate↗
PubMed1995

Low expression of adhesion molecules in a case of cutaneous T-cell lymphoma.

A case of cutaneous T-cell lymphoma (CTCL) with low expression of the adhesion molecules lymphocyte function-associated antigen-1 (LFA-1), intercellular adhesion molecule-1 (ICAM-1), and very late antigen-4 (VLA-4) is described. The patient was a 90-year-old man with red round homogeneous tumors on his scalp, trunk, and extremities. He had no history of definite erythema or plaque stage. A biopsy sample taken from a tumor revealed massive infiltration of atypical lymphocytes in the reticular dermis and subcutis with a definite clear zone. The atypical lymphocytes were medium-sized with slightly convoluted nuclei. Immunohistochemically, the infiltrates showed the phenotype of so-called memory T cells. On the basis of these features, the case was diagnosed as CTCL. Expression of LFA-1, ICAM-1 and VLA-4 on the infiltrates was 9%, 13% and 11%, respectively, which is much lower than that in classic mycosis fungoides. This finding suggests that loss of these adhesion molecules may contribute to loss of epidermotropism in the advanced stage of CTCL.

Aged↗
PubMed1995

Cloning of cDNAs encoding mammalian double-stranded RNA-specific adenosine deaminase.

Double-stranded RNA (dsRNA)-specific adenosine deaminase converts adenosine to inosine in dsRNA. The protein has been purified from calf thymus, and here we describe the cloning of cDNAs encoding both the human and rat proteins as well as a partial bovine clone. The human and rat clones are very similar at the amino acid level except at their N termini and contain three dsRNA binding motifs, a putative nuclear targeting signal, and a possible deaminase motif. Antibodies raised against the protein encoded by the partial bovine clone specifically recognize the calf thymus dsRNA adenosine deaminase. Furthermore, the antibodies can immunodeplete a calf thymus extract of dsRNA adenosine deaminase activity, and the activity can be restored by addition of pure bovine deaminase. Staining of HeLa cells confirms the nuclear localization of the dsRNA-specific adenosine deaminase. In situ hybridization in rat brain slices indicates a widespread distribution of the enzyme in the brain.

Adenosine Deaminase↗
PubMed1995

Screening of tissue cultures and thalli of lichens and some of their active constituents for inhibition of tumor promoter-induced Epstein-Barr virus activation.

Inhibition of tumor promoter-induced Epstein-Barr virus (EBV) activation was screened using tissue culture and thallus extracts of lichens. Usnea longissima ACH. thallus and Cetraria ornata MULL. ARG. tissue culture showed strong inhibitory activity. We identified (+)-usnic acid (1), barbatic acid (2), diffractaic acid (3), 4-O-demethylbarbatic acid (4), and evernic acid (5) as inhibitors of EBV activation from the U. longissima thallus. Of these compounds, (+)-usnic acid exhibited the highest inhibitory activity (IC50 = 1.0 microM).

Anticarcinogenic Agents↗
PubMed1995

Partial purification and some properties of a neutral proteinase in rat ovary.

The ovary of rat possessed a neutral proteinase which had an optimum pH at around 8.5 in the presence of 0.5 M NaCl. The proteinase was soluble only in media of high ionic strength such as 2 M NaCl. In order to prevent the reprecipitation in media of low ionic strength of the enzyme solubilized, it is necessary to add protamine sulfate to the solubilizing medium. When the solubilized enzyme was applied to a Sephadex column, the proteinase activity was eluted at the same position as bovine alpha-chymotrypsinogen. The results using some protease inhibitors showed that the proteinase was a chymotrypsin-like serine enzyme. When rats were treated with compound 48/80, the proteinase activity almost completely disappeared, suggesting that the enzyme is of mast cell origin.

Animals↗
PubMed1995

Effects of rhG-CSF on infection complications and impaired function of neutrophils secondary to chemotherapy for non-Hodgkin's lymphoma. Hokkaido Study Group of Malignant Lymphoma, and rhG-CSF, Japan.

It has been previously demonstrated that the administration of recombinant human granulocyte-colony stimulating factor (rhG-CSF) ameliorates the decrease of the polymorphonuclear neutrophils (PMNs) count after the cytotoxic chemotherapies, thereby reducing the infection complications associated with neutropenia. In this multi-center study, we studied the prophylaxtic effect of rhG-CSF administration on infection complications in patients with non-Hodgkin malignant lymphoma, who received cytotoxic chemotherapies (CHOP or ProMACE/CytaBOM). rhG-CSF administration reduced the frequency of infection complications, and there was no obvious difference in it's frequency between the CHOP-treated and the ProMACE/CytaBOM-treated groups when administered with rhG-CSF, thereby indicating that third generation therapy for NHL may be safely completed in Japanese in combination with rhG-CSF administration. Furthermore, we investigated both the in vitro and the in vivo effects of rhG-CSF on the function of PMNs in patients with NHL and healthy donors, and revealed that the administration of rhG-CSF for NHL patients receiving cytotoxic chemotherapy brought on an improvement of the production of active oxygen but did not affect serum levels of IFNs, IL-1-beta, and IL-6, inspite of a slight elevation of TNF-alpha. Consistent with these results, in vitro treatment of PMNs with rhG-CSF induced no significant production of these inflammatory cytokines and their mRNA expressions. Furthermore, rhG-CSF administration showed no significant effects in vivo on the expression of CD11a, CD11b and LECAM-1 on PMNs and integrins on platelets.

Adult↗