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Biomedical subjects

K Ohta

Publications and source records attributed to K Ohta.

At least 253 records · Page 14Linked to original sources

Successful treatment using peroral itraconazole in a patient with acute promyelocytic leukemia complicated with splenic candidiasis.

A 57-year-old female with acute promyelocytic leukemia was admitted to our hospital. The PML-RAR alpha fusion transcript was reverse transcription polymerase chain reaction. Complete remission was achieved with intensive induction chemotherapy. Then a high fever unresponsive to antibiotics with increased C-reactive protein continued. Abdominal computed tomography revealed multiple low-density lesions in the spleen. Splenic candidiasis was suspected and peroral treatment with itraconazole (200 mg/day) was begun. After the fungal infection was confirmed to be inactive, splenectomy was performed. The splenic tissue showed multiple white or yellow nodules and methenamine silver stain revealed fungal hyphae characteristic to Candida. There was no evidence of relapse of Candida infection. She has been in complete remission for these two years and free of fungal infection. It is indicated from our case that splenic candidiasis in patients with acute myeloid leukemia can be successfully treated with oral administration of itraconazole and subsequent splenectomy, when it is confined in the spleen.

Antifungal Agents↗

An effective method for recovering CD34 positive progenitor cells from peripheral blood stem cell apheresis products cryopreserved with simplified method.

The use of small volume collection chamber (SVCC) during peripheral blood stem cell (PBSC) apheresis, combined with simplified cryopreservation without rate-controlled freezing, have successfully been applied to clinical PBSC transplantation following myeloablative chemotherapies. However, the method to effectively select CD34+ progenitor cells from frozen apheresis products obtained with these simplified methods has not been reported. For this goal, after washing the thawed apheresis products with medium containing Dnase I, two different approaches to purify CD34+ progenitor cells from washed WBCs were compared. In method I, CD34+ cells were purified on the same day using immunomagnetic method. In method II, the cells after wash were cultured for overnight in RPMI-1640/10% FCS containing SCF and IL-3, followed by enrichment of CD34+ cells as in method I on the next day. In both methods, CD34+ cells were recovered with high viability. However, subsequent liquid culture revealed that the cells obtained from method II have clearly higher growth potential compared with the cells from method I. In addition, these CD34+ cells from method II well-tolerated to further refreeze and thaw. Thus, allowing to "rest" overnight after thaw may be critical for processing of the simply cryopreserved apheresis products as in method II.

Adult↗

Incidence of abnormalities in laboratory tests found in surveillance of adults over 40 years of age.

National health check-up systems have been used for 5 years in Japan for adults who are over 40 years of age. As part of a national project, Osaka prefecture is also conducting a program for health check-up testing and cancer screening for this age group. This surveillance revealed that incidence of obesity, hypertension, cholesterolemia, albuminuria, or abnormal ECG was high. Analysis of surveillance results should contribute to understanding the present status and recent trends in diseases in the aged. With continuation of this surveillance for a number of years, trends in life-style related diseases in Japan should be detectable.

Adult↗

Fluorescence derivatizing procedure for 5-hydroxytryptamine and 5-hydroxyindoleacetic acid using 1,2-diphenylethylenediamine reagent and their sensitive liquid chromatographic determination.

A pre-column derivatization method using a fluorogenic reagent, 1,2-diphenylethylenediamine (DPE) was studied for the sensitive HPLC determination of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA), which are biosubstances used in the diagnosis of several diseases. For the quantitative determination, the biogenic indole compounds were converted to their corresponding fluorescent derivatives with DPE in the presence of potassium hexacyanoferrate (III) at room temperature, and then the derivatives were separated by reversed-phase liquid chromatography with fluorescence detection. The chromatographic detection limits of the fluorescent peaks at a signal-to-noise ratio of 3 were 0.3 fmol for 5-HT and 0.2 fmol for 5-HIAA. The proposed method permits the simultaneous quantification of 5-HT and 5-HIAA at concentrations higher than 2.4 nM in human urine without a clean-up procedure.

Chromatography, High Pressure Liquid↗

Distinct roles of two separable in vitro activities of yeast Mre11 in mitotic and meiotic recombination.

UNLABELLED: In Saccharomyces cerevisiae, Mre11 protein is involved in both double-strand DNA break (DSB) repair and meiotic DSB formation. Here, we report the correlation of nuclease and DNA-binding activities of Mre11 with its functions in DNA repair and meiotic DSB formation. Purified Mre11 bound to DNA efficiently and was shown to have Mn2+-dependent nuclease activities. A point mutation in the N-terminal phosphoesterase motif (Mre11D16A) resulted in the abolition of nuclease activities but had no significant effect on DNA binding. The wild-type level of nuclease activity was detected in a C-terminal truncated protein (Mre11DeltaC49), although it had reduced DNA-binding activity. Phenotypes of the corresponding mutations were also analyzed. The mre11D16A mutation conferred methyl methanesulfonate-sensitivity to mitotic cells and caused the accumulation of unprocessed meiotic DSBs. The mre11DeltaC49 mutant exhibited almost wild-type phenotypes in mitosis. However, in meiosis, no DSB formation could be detected and an aberrant chromatin configuration was observed at DSB sites in the mre11DeltaC49 mutant. These results indicate that Mre11 has two separable functional domains: the N-terminal nuclease domain required for DSB repair, and the C-terminal dsDNA-binding domain essential to its meiotic functions such as chromatin modification and DSB formation. KEYWORDS: DNA binding/double-strand break repair/DSB formation/Mre11/nuclease

Bacteriophage M13↗

Intracellular localization and release of eotaxin from normal eosinophils.

Eotaxin is a potent and selective CC chemokine for eosinophils and basophils. We established several monoclonal antibodies (Mabs) allowing the neutralization and measurement of human eotaxin. Using the Mabs as probes, we demonstrated that normal eosinophils contained intracellular granule-associated eotaxin. Quantification of cell-associated eotaxin in different leukocyte subsets revealed that it was principally expressed in eosinophils. Finally, we showed that normal eosinophils released eotaxin upon stimulation with either of two secretagogues, C5a or ionomycin. These findings raise the possibility that eosinophil-derived eotaxin contributes to the local accumulation of eosinophils at the site of inflammation.

Animals↗

Developmental changes and functional properties of human memory T cell subpopulations defined by CD60 expression.

The present study was undertaken to examine developmental changes of T cells expressing CD60 and their functional properties. Three-color immunofluorescence analysis revealed that the CD60 antigen was preferentially expressed on a proportion of memory (CD45RO+) CD4+ T cells, but less on memory CD8+ T cells, while this antigen is undetectable in naive (CD45RO-) T cells. A frequency of memory CD4+ T cells expressing CD60 in the peripheral blood was negligible in newborns and gradually increased with advancing age. CD60+ memory CD4+ T cells showed stronger proliferative responses to PPD and produced higher levels of IL-4 and IL-10 than CD60- ones, whereas production of IL-2 and IFN-gamma was similarly found in both cell subpopulations. In addition, it was shown that efficient helper activity for Ig production by B cells was predominated in CD60+ memory CD4+ T cells. These results suggest that CD60 may be primarily expressed on the functionally differentiated memory effector cells among circulating CD45RO+ CD4+ T cells.

Adolescent↗

Ion-exchange chromatography of mono- and divalent cations in natural waters on a weak-acid anion-exclusion column.

Ion-exchange chromatography with indirect conductimetric detection for the simultaneous determination of mono- and divalent cations is investigated using an anion-exclusion chromatographic column packed with polymethacrylate-based weakly acidic cation-exchange resin in the H+ form (Tosoh TSKgel OA-PAK-A, 300 mm x 7.8 mm I.D.). An eluent comprising a strong acid, a weak organic acid, methanol and water is used. Using 0.75 mM sulfuric acid, 2 mM tartaric acid, 7.5% (v/v) methanol in water as eluent, the monovalent cations (Na+, NH4+, and K+) and divalent cations (Mg2+ and Ca2+) were separated simultaneously by a cation-exchange mechanism in about 25 min. The application of this method to the analysis of several natural waters including rain, river, lake, underground and forest soil waters for estimating acid rain effects on the natural and urban environments is presented.

Acid Rain↗

Unique binding pocket for KW-4679 in the histamine H1 receptor.

The histamine H1 receptor has an aspartate (Asp) residue in transmembrane helix 3 (TM3), which is well-conserved among biogenic amine receptors. The Asp residue is one of the most crucial amino acids for ligand binding. The tested histamine H1 receptor antagonists with tri- and tetracyclic structures were not selective for histamine H1 receptors and showed affinity for several other biogenic amine receptors. In contrast, KW-4679 ((Z)-11-[3-(dimethylamino)propylidene]-6,11-dihydrodibenz[b, e]oxepin-2-acetic acid hydrochloride), a tricyclic compound, was a selective histamine H1 receptor antagonist. [3H]KW-4679 had high affinity (Kd value of 2.5 +/- 0.12 nM) for wild-type human histamine H1 receptors. In the [3H]KW-4679 binding assay, replacement of Asp107 by alanine by site-directed mutagenesis greatly reduced the affinities (280-2100-fold) of tri- and tetracyclic compounds, whereas this mutation led to a comparatively small reduction (14-fold) in KW-4679 affinity. These results demonstrate that the tested tri- and tetracyclic histamine H1 receptor antagonists which have a tight interaction with the Asp residue are not selective for the histamine H1 receptor. Furthermore, the high selectivity of KW-4679 might be explained by a unique binding pocket, which consists of the Asp residue and other acceptor sites, in the histamine H1 receptor.

Animals↗

Studies on inhibitors of mammalian DNA polymerase alpha and beta: sulfolipids from a pteridophyte, Athyrium niponicum.

Three sulfolipid compounds, 1, 2, and 3, have been isolated from a higher plant, a pteridophyte, Athyrium niponicum, as potent inhibitors of the activities of calf DNA polymerase alpha and rat DNA polymerase beta. The inhibition by the sulfolipids was concentration dependent, and almost complete inhibition of DNA polymerase alpha and DNA polymerase beta was achieved at 6 and 8 microg/mL, respectively. The compounds did not influence the activities of calf thymus terminal deoxynucleotidyl transferase, prokaryotic DNA polymerases such as the Klenow fragment of DNA polymerase I, T4 DNA polymerase and Taq polymerase, the DNA metabolic enzyme DNase I, and even a DNA polymerase from a higher plant, cauliflower. Similarly, the compounds did not inhibit the activity of the human immunodeficiency virus type 1 reverse transcriptase. The kinetic studies of the compounds showed that DNA polymerase alpha was inhibited non-competitively with respect to the DNA template and substrate, whereas DNA polymerase beta was inhibited competitively with both the DNA template and substrate. The binding to DNA polymerase beta could be stopped with non-ionic detergent, but the binding to DNA polymerase alpha could not.

Animals↗

Mutations in the MRE11, RAD50, XRS2, and MRE2 genes alter chromatin configuration at meiotic DNA double-stranded break sites in premeiotic and meiotic cells.

In the yeast Saccharomyces cerevisiae, meiotic recombination is initiated by DNA double-stranded breaks (DSBs) occurring in micrococcal nuclease (MNase)-hypersensitive regions of the chromatin. MNase-sensitive sites also undergo meiosis-specific alterations in chromatin structure prior to the appearance of DSBs. DSB formation requires the products of numerous genes. Herein we have examined the effects of mutations in four such genes, MRE11, RAD50, XRS2, and MRE2, on MNase sensitivity at DSB sites in premeiotic and meiotic cells. Disruption mutations in each of four genes confer greater than wild-type levels of MNase sensitivity in premeiotic cells. In meiotic prophase, all of these mutations affect MNase sensitivity at DSB sites and fall into two distinct phenotypic classes. The type 1 mutations (mre2 and mre11) confer a reduction in MNase sensitivity relative to the wild-type level. The type 2 mutations (rad50 and xrs2) permit a meiotic increase in the MNase sensitivity to reach a final level higher than that observed in wild-type cells. An mre11 disruption mutation (type 1) is epistatic to a rad50 null mutation (type 2) with respect to its meiotic effects on MNase sensitivity, suggesting that the events observed in the type 2 mutants during meiosis are dependent upon type 1 functions. One interpretation of these results is that Mre11, Rad50, Xrs2, and possibly Mer2 (whose splicing is Mre2-dependent) form a complex at recombination hot spots and establish a chromatin/DNA configuration favorable for the induction of DSBs.

Chromatin↗

Expression of HNF-1 alpha and HNF-1 beta in various histological differentiations of hepatocellular carcinoma.

Hepatic nuclear factor 1 (HNF-1) regulates genes in a hepatocyte-specific manner. It has been previously reported that the ratio of HNF-1 alpha and HNF-1 beta mRNA is related to histological differentiation hepatocellular carcinoma (HCC). In this study, the expression levels of the HNF-1 alpha and HNF-1 beta proteins were analysed relatively and quantitatively in various histologically differentiated HCC and surrounding non-cancerous tissues, and HNF-1 alpha binding activity for the AT element of the B domain of the human alpha-fetoprotein enhancer was examined. Western blot analysis demonstrated that HNF-1 alpha protein was expressed at a higher level in well-differentiated HCC tissues than in the surrounding non-HCC tissues; on the other hand, the HNF-1 alpha protein was expressed at lower levels in moderately and poorly differentiated HCCs than in the surrounding non-HCC tissues. The levels of HNF-1 beta expression in well-differentiated and poorly differentiated HCCs were similar to and higher than those found in the respective surrounding non-cancerous portions. In binding assays, HNF-1 binding activity was high in well-differentiated HCC and lower in moderately and poorly differentiated HCCs. Most well-differentiated HCC cases showed immunohistochemical expression of HNF-1 alpha. These findings show that poor histological differentiation of HCC correlates with decreases in the level and activity of HNF-1 alpha proteins.

Blotting, Western↗

Intestinal absorption and analgesic activity of aminopeptidase-resistant cellobiose-coupled leucine enkephalinamide.

Leucine enkephalinamide (LEamide), aminopeptidase-degradable opioid peptide, was coupled with cellobiose (cellobiose-coupled LEamide, CcpLEamide). CcpLEamide was absorbed from the rat small intestine in vitro, whereas LEamide was not. CcpLEamide on the mucosal side was more stable than aminopeptidase-resistant cellobiose-coupled leucine enkephalin (CcpLE) in the presence of inhibitors of enkephalinase and angiotensin converting enzyme, and much more stable than LEamide. The absorption rate (clearance) of CcpLEamide was comparable with that of CcpLE in the presence of these peptidase inhibitors. Analgesic activities of these enkephalins were tested by the acetic acid writhing assay and hot-plate assay after subcutaneous administration to mice. Both assays indicated CcpLEamide-induced analgesia. On the other hand, the analgesic activity of LEamide was not observed, but pretreatment with amastatin (a peptidase inhibitor) produced LEamide-induced analgesia. These results indicate that CcpLEamide is stable in the body and has analgesic effects without pretreatment with peptidase inhibitors, and was stable enough to be absorbed from the small intestine. We propose CcpLEamide as an orally active analgesic peptide candidate.

Aminopeptidases↗

Expression of Fas antigen on helper T lymphocytes in Vogt-Koyanagi-Harada disease.

BACKGROUND: Our purpose was to analyze the expression of Fas antigen on CD4+ lymphocytes in the aqueous humor (AH) and cerebrospinal fluid (CSF) of patients with Vogt-Koyanagi-Harada disease (VKH). METHODS: Using three-color flow cytometry, we assessed T-lymphocyte subsets stained with fluorescence-conjugated anti-CD3, CD4, CD8, CD29, CD45RA, CD45RO, HLA-DR, and Fas monoclonal antibodies in AH, CSF and peripheral blood (PB) from 8 patients with active VKH. RESULTS: CD3+ T cells constituted the majority of lymphocytes in AH and CSF, in contrast to with PB. The percentages of CD4+ lymphocytes in uveitic AH and CSF were significantly higher than that in PB (P < 0.01). Activated CD4+ and CD8+ cells were significantly more frequent in AH than in CSF and PB (P < 0.01). Although the percentages of CD45RA+ cells within CD4+ cells in AH and CSF were extremely low compared with those in PB, the proportions of CD29+ and CD45RO+ (memory) cells within CD4+ were much higher than those in PB (P < 0.01). Fas antigen was also highly expressed on such CD4+ cells in AH, as in other uveitis patients and on such cells in CSF. Moreover, the percentages of Fas+ and memory cells in AH were significantly higher than those in CSF. CONCLUSIONS: The majority of CD4+ lymphocytes in AH and CSF from patients with active VKH were activated memory cells, on which Fas antigen was also highly expressed. Although this Fas expression may not be an apoptosis-related phenomenon, accumulation of Fas+ memory T lymphocytes in AH and CSF probably reflects the immunopathologic mechanism of VKH.

Adult↗

Normal ontogenic observations on the expression of Eph receptor tyrosine kinase, Cek8, in chick embryos.

The spatio-temporal pattern of expression for the Eph receptor tyrosine kinase, Cek8, was observed in normal chick embryos from H-H stage 6 to 23 by immunohistochemical techniques. Expression of Cek8 was already present in embryos at H-H stage 6, where it was located in the neural plate of the brain region, paraxial mesoderm, and the primitive streak. Regions expressing Cek8 subsequently increased during development to include the neural folds of the brain, rhombomeres 3 and 5, the caudal part of the neural plate, neural crest cells related to the formation of glossopharyngeal nerve ganglia, invaginated cells throughout the primitive groove and the epithelium of the rudiment of the gall bladder. Cek8 was also expressed in the mesenchymal cells of the pharyngeal arches, allantoic stalk and limb buds as well as in the areas surrounding the eye vesicles and nasal pits. Furthermore, cells in the tail bud progressing to the secondary neurulation expressed Cek8. Thus, the spatiotemporal patterns of Cek8 expression appears to have intimate relationships with tissue rebuilding, the maturation of differentiated cells, and the spatial organization of tissues. Consequently, it appears that Cek8 plays an integral role in the developmental events leading to the formation of a wide--though not inclusive--variety of tissues and organ systems.

Animals↗