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Biomedical subjects

Y Mishima

Publications and source records attributed to Y Mishima.

At least 37 records · Page 2Linked to original sources
PubMed2000

Electrochemical characterization and DNA-binding property of dipyridophenazine complexes of osmium (II).

Novel dipyridophenazine (DPPZ) complexes of osmium (II), [Os(L)2(DPPZ)]2+ [L = 2,2'-bipyridyl (bpy)(1), 4,4'-diamino-2,2'-bipyridyl (DA-bpy)(2), 4,4'-dimethyl-2,2'-bipyridyl(DM-bpy)(3), and 4,4'-dicarboxyl-2,2'-bipyridyl (DC-bpy)(4)] have been synthesized and characterized. The DNA-binding properties of the complexes were studied by electrochemical methods. As the results, complex 2 shows higher affinity to DNA than other osmium complexes. The binding constant, K of complex 2 to calf thymus DNA has been determined to be 2.3 x 10(7) M-1 by normal pulse voltammetry (NPV).

Animals↗
PubMed2000

Biodistribution of boron concentration on melanoma-bearing hamsters after administration of p-, m-, o-boronophenylalanine.

Although p-boronophenylalanine (p-BPA), a boronate analogue of tyrosine, has proven to be one of the most successful compounds for boron neutron capture therapy (BNCT) of malignant melanoma, the selective uptake mechanism of this compound into melanoma cells is not well understood. Therefore, the relationship between the structure of BPA and its specific affinity to melanoma cells appears worthy of investigation. In the present study, m- and o-boronophenylalanine (m- and o-BPA) were administered to melanoma-bearing hamsters and their uptake was measured. The time courses (0.5, 2.0, 4.0 and 48.0 h) of boron concentrations in melanoma, normal skin, and blood were determined in male Syrian (golden) hamsters bearing Greene's melanomas following a single intraperitoneal injection of either p-, m- or o-BPA (100 mg/kg of BPA fructose in 1.0 ml of saline). The boron concentrations in these tissues were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). In melanoma, the order of boron uptake was p- > m- > o-BPA at all time points, and the boron concentrations obtained with p-BPA and m-BPA resembled each other in that they had a peak at 2 h after administration and decreased with time. The melanoma/skin boron concentration ratio of p-BPA had a peak at 4 h after administration and the ratio ranged between 7/1 and 8/1. On the other hand, m-BPA and o-BPA had a peak at 2 h and their ratios ranged between 4/1 and 5/1. The difference in the accumulations of p-BPA and m-BPA could be due to a difference in the property of p-BPA as a tyrosine analogue for melanin synthesis. The accumulation of m-BPA into melanoma might indicate the baseline level of metabolism-related amino acid transport. Our experimental findings indicate that this melanin synthesis, or the structural analogy between the boron compound and tyrosine as a precursor of melanin, is an important factor in the increased accumulation of p-BPA in melanoma cells.

Animals↗
PubMed2000

A novel bacterial ATP-binding cassette transporter system that allows uptake of macromolecules.

A gram-negative bacterium, Sphingomonas sp. strain A1, isolated as a producer of alginate lyase, has a characteristic cell envelope structure and forms a mouth-like pit on its surface. The pit is produced only when the cells have to incorporate and assimilate alginate. An alginate uptake-deficient mutant was derived from cells of strain A1. One open reading frame, algS (1,089 bp), exhibiting homology to the bacterial ATP-binding domain of an ABC transporter, was cloned as a fragment complementing the mutation. algS was followed by two open reading frames, algM1 (972 bp) and algM2 (879 bp), which exhibit homology with the transmembrane permeases of ABC transporters. Disruption of algS of strain A1 resulted in the failure to incorporate alginate and to form a pit. Hexahistidine-tagged AlgS protein (AlgS(His6)) overexpressed in Escherichia coli and purified by Ni(2+) affinity column chromatography showed ATPase activity. Based on these results, we propose the occurrence of a novel pit-dependent ABC transporter system that allows the uptake of macromolecules.

ATP-Binding Cassette Transporters↗
PubMed2000

Selective uptake of para-boronophenylalanine increases in amelanotic melanoma cells transfected by the tyrosinase gene.

To investigate the mechanism of uptake of para-boronophenylalanine (p-BPA), a capture agent for boron neutron capture therapy (BNCT) of melanoma and brain tumour, into melanoma cells, we studied the relationship between melanin synthesis and the concentration of boron using tyrosinase-deficient mouse amelanotic melanoma cells (A1059) and melanotic melanoma cells (TA1059). A1059 was established from mouse B16F10 cells, and TA1059 was constructed by transfecting human tyrosinase cDNA into A1059. The melanin content of TA1059 was 1.5-fold higher than that of B16F10, and was undetectable in A1059. The order of p-BPA uptake was TA1059 > B16F10 > A1059 at the time points examined, and the boron content of TA1059 was approximately 1.5-fold higher than that of B16F10. Our experimental findings indicated that melanin synthesis is a very important factor for characterizing the increase in accumulation of p-BPA in melanoma cells. A significant difference in boron uptake into TA1059 was observed between p-BPA and meta-BPA (m-BPA), but there were no apparent differences in the case of A1059. The difference in accumulation of p-BPA and m-BPA could be due to differences in the properties of p-BPA as a tyrosine analogue needed for melanin synthesis.

Animals↗
PubMed2000

[Problems concerning the prices of surgical operations in Japan. Union of Social Medical Insurance Committee Members of Surgical Societies in Japan].

The Union of Social Medical Insurance Committee Members of Surgical Societies in Japan was established in 1967. The union has tried to develop scientific methods to assess the price of surgical operations in Japan and proposed a tentative plan for the assessment of the price of operations. The price of an operation includes personnel expenses and other costs such as the prime costs to repay loans for land and buildings, and taxes. Personnel expenses are calculated by the grade of technical difficulties, the number of doctors and nurses and the duration of the operation. A more precise method to judge the difficulties of the operation seems to be necessary. To examine the recent increase in expenses for surgical materials, the cooperation of main hospitals authorized by surgical societies will be necessary. The prices of surgical operations presented by the Ministry of Health and Welfare of Japan correlated well with the prices proposed by the Union.

Fee-for-Service Plans↗
PubMed1999

NH2-terminal pentapeptide of endothelial interleukin 8 is responsible for the induction of apoptosis in leukemic cells and has an antitumor effect in vivo.

We have reported that endothelial interleukin 8 (IL-8) induces apoptosis in leukemic cells in vitro and in vivo, and that interaction between endothelial cells and leukemic cells causes induction of apoptosis through the release of endothelial IL-8 (Y. Terui et al., Biochem. Biophys. Res. Commun., 243: 407-411, 1998; Y. Terui et al., Blood, 92: 2672-2680, 1998). Here, we examined whether a pentapeptide corresponding to the NH2-terminal region of endothelial IL-8 can induce apoptosis in leukemic cells. The NH2-terminal pentapeptide Ala-Val-Leu-Pro-Arg (AVLPR) was found to significantly induce apoptosis in the leukemic cell lines K562, HL-60, Jurkat, and Daudi, as compared with the COOH-terminal pentapeptide Arg-Glu-Ala-Asn-Ser (REANS). Moreover, the NH2-terminal pentapeptide AVLPR significantly inhibited growth of i.p. and s.c. tumor masses of K562 cells and induced apoptosis in these cells in vivo. The active site of endothelial IL-8 is the NH2-terminal pentapeptide AVLPR, and this may serve as a new therapy for hematological malignancies.

Animals↗
PubMed1999

Beta(2)-microglobulin identified as an apoptosis-inducing factor and its characterization.

Major histocompatibility complex (MHC) molecules play an important role in antigen presentation for induction of tumor as well as cellular and humoral immunities. Recent studies using anti-MHC antibodies demonstrated that antibodies specific for HLA class I molecules induced cellular activation and a type of apoptosis that may be distinct from Fas-dependent or TNFR (tumor necrosis factor-alpha receptor)-dependent processes. We purified a previously untested apoptosis-inducing factor from HL-60 human leukemic cell-conditioned media to homogeneity and sequenced it. It was identified as beta(2)-microglobulin (beta(2)m), which has been previously known as thymotaxin and is a part of the HLA class I antigen complex. beta(2)m acts on both T-leukemic cells and myeloid leukemic cells to induce apoptosis, which then activates caspase 1 and 3. Cross-linking studies showed that biotinilated beta(2)m recognized an epitope distinct from those recognized by the anti-HLA class I antibody, as reported previously. We demonstrated that beta(2)m plays a previously unrecognized and important role in regulating the elimination of tumor cells, which occurs as a result of the action of beta(2)m as an apoptosis-inducing factor.

Amino Acid Chloromethyl Ketones↗
PubMed1999

Compact chromatin packaging of inactive X chromosome involves the actively transcribed Xist gene.

The Xist gene responsible for X inactivation may take a unique chromatin structure because of exceptional expression from inactive X Chromosome, (Chr). We have examined differential chromatin packaging of the Xist gene region between active and inactive X Chr with a novel method consisting of the chromatin fractionation and allele-specific detection. Analysis of F1 heterozygous female mice from T(X;16)16H x MSM crosses and two cell clones derived from inter-subspecific F1 female mice demonstrated that the packaging level of the transcribed Xist region on inactive X Chr was as tight as that of the repressed Pgk-1 allele on the same chromosome. On the other hand, restriction endonuclease sensitivity assay of chromatin showed that the promoter region, but not transcribed regions, of the transcribed Xist allele retained accessibility to nucleases. These results may suggest a cis-element(s) in a regulatory region of the Xist gene to prevent the transcriptionally inhibitory effect of the chromatin packaging.

Animals↗
PubMed1999

Enzymatic and genetic bases on assimilation, depolymerization, and transport of heteropolysaccharides in bacteria.

When microorganisms utilize macromolecules for their growth, they commonly produce extracellular depolymerization enzymes and then incorporate the depolymerized low-molecular-weight products. Assimilation of heteropolysaccharides (gellan and xanthan) by Bacillus sp. GL1 depends on this generally accepted mechanism. On the other hand, Sphingomonas sp. A1 represents an unexplored specific and interesting system for macromolecule assimilation. In the presence of heteropolysaccharide (alginate), the bacterium forms a mouthlike pit on its cell surface and directly incorporates the macromolecule using a novel ATP-binding cassette transporter (ABC transporter). In this review, we discuss enzymatic and genetic bases on the depolymerization and assimilation routes of heteropolysaccharides in bacteria, with particular emphasis on the novel incorporation system for macromolecules, characteristic post-translational modification processes of polysaccharide lyases and on the mouthlike pit structure on the bacterial cell surface.

Journal Article↗
PubMed1999

Special cell surface structure, and novel macromolecule transport/depolymerization system of Sphingomonas sp A1.

A bacterium isolated from soil as an alginate lyase producer shows characteristic morphological and taxonomical properties consistent with being classified in the genus Sphingomonas. The bacterium utilizes high molecular weight (HMW)-alginate for growth by depolymerization of the polymer with intracellular alginate lyases, which are generated from a common precursor protein through autoregulated post-translational modifications. Electron microscopic observations of the cell surface and of thin sections of cells grown on HMW-alginate revealed dynamic changes in both cell surface and membrane structures. The most remarkable change is recognized in the formation of mouth-like pits which open and close depending on the presence or absence of HMW-alginate. Enzymatic and genetic analyses of HMW-alginate incorporation processes confirmed the presence of a pit-dependent and macromolecule-specific ABC transporter system in cells of Sphingomonas species A1. This is the first description of a bacterium with a pit on the cell surface and a pit-dependent endocytosic uptake system for macromolecules.

Journal Article↗
PubMed1999

DNA hybridization sensor utilizing [Os(5,6-dmphen)3]2+ by square wave voltammetry.

DNA hybridization detection utilizing [Os(5,6-dmphen)3]2+ (tris(5,6-dimethyl-phenanthroline) osmium(II/III)) as hybridization indicator was studied, because [Os(5,6-dmphen)3]2+ has the most largest association constant (K2+) and high current density in osmium methyl substituted phenanthroline complexes. As the result, target DNA could be detected selectively ranging from 6.9 x 10(-10) to 6.9 x 10(-5) g/mL using square wave voltammetry.

Base Sequence↗
PubMed1999

Pharmacokinetics of 10B-p-boronophenylalanine in tumours, skin and blood of melanoma patients: a study of boron neutron capture therapy for malignant melanoma.

To optimize the neutron dose for boron neutron capture therapy (BNCT), the boron-10 (10B) concentration kinetics of 10B-p-boronophenylalanine (BPA) were analysed in 22 melanoma patients with primary or metastatic melanomas who received BPA and subsequently underwent BNCT or surgery. The blood concentration in nine patients receiving 179.7+/-14.9 mg/kg BPA increased with time during intravenous infusion, peaked at the end of administration and decreased thereafter. The peak values at the end of administration were 9.4 2.6 microg 10B/g blood, and half-lives for the initial and second components of the blood clearance were 2.8 and 9.2 h, respectively. Skin concentrations in the 10 patients varied from case to case; however, skin-to-blood ratios were relatively constant at 1.31+/-0.22 during the 6 h after the end of administration. Boron concentrations in the tumours resected from the seven patients who were operated on decreased in parallel to the blood values, the tumour-to-blood ratio being relatively constant at 3.40+/-0.83. The present analytical data of BPA pharmacokinetics support our previous approach for optimizing the timing of irradiation and setting the neutron flux large enough for tumour eradication but still tolerable for normal skin.

Adult↗
PubMed1999

Expression of tyrosinase, TRP-1 and TRP-2 in ultraviolet-irradiated human melanomas and melanocytes: TRP-2 protects melanoma cells from ultraviolet B induced apoptosis.

Tyrosinase related protein (TRP)-1 and TRP-2 are known to regulate the quality of melanin, and recently their potential role in inhibiting apoptosis have also been reported. To study the role of tyrosinase, TRP-1 and TRP-2 in the growth, differentiation and cell death of ultraviolet B (UVB) irradiated melanocytes, the expression of these proteins in amelanotic and melanotic cells was examined. Expression of tyrosinase and TRP-1 correlated with melanin content, which was upregulated after repeated irradiation of melanotic cells by low doses of UVB. In contrast, the expression and activity of TRP-2 correlated with cell proliferation, but not with pigmentation. In one melanotic melanoma cell line, significant suppression of cell proliferation was observed after low or high doses of UVB irradiation, possibly due to apoptotic changes. TRP-2 expression was remarkably reduced in UVB-irradiated cells, and transfection with TRP-2 expression vector rescued these cells from UVB-induced apoptosis. These results indicate that TRP-2 expression is closely associated with the regulation of cell growth/survival of melanocytes exposed to UVB and that TRP-2 plays a role in protecting melanoma cells from UVB-induced apoptosis.

Adult↗
PubMed1999

Horizontal and vertical pigment spread into surrounding piebald epidermis and hair follicles after suction blister epidermal grafting.

Following the earlier description of Carnot and Deflandre in 1896, pigment spread phenomenon in mammals was investigated using immunogenetically marked melanocytes (Billingham and Silver, Quart. Rev. Biol. 1960 35: 1-40; Billingham and Silver, Ann. N.Y. Acad. Sci. 1963 100: 348-363). In spite of a number of similar studies on vitiligo lesions, detailed evaluation of pigment spread in piebald lesions has not been reported. To gain further insight into the pigment spread phenomenon in human skin, five piebald patients were studied, on whom suction blister epidermal grafting therapy onto piebald patches was performed. In the present study, pigmentation of all epidermal grafts from normally pigmented areas spread horizontally. It was also found that pre-existing white hairs in recipient sites became pigmented within 1 year after epidermal grafting. Immunofluorescence studies using melanocyte-specific antibody NKI/beteb revealed the newly induced presence of melanocytes in the newly pigmented hair follicles. Further, to study the possible mechanisms inhibiting melanocyte migration from normal skin into piebald lesions, epidermis was grafted from border zones (containing both normal and piebald skin) into the center of hypopigmented lesions. Melanocytes clearly migrated through the border zone of grafted epidermis into surrounding recipient hypopigmented sites.

Epidermis↗
PubMed1999

[Serum soluble interleukin-2 receptor in patients with pulmonary mycobacterial diseases].

Serum soluble interleukin-2 receptor (sIL-2R) levels were measured in patients with untreated pulmonary tuberculosis (24 cases), patients with multidrug-resistant intractable pulmonary tuberculosis (7 cases) and patients with pulmonary non-tuberculous mycobacteriosis (27 cases). Serum sIL-2R levels were elevated in patients with pulmonary mycobacterial diseases and were elevated in untreated pulmonary tuberculosis patients than in other patients. In patients with new tuberculosis, serum sIL-2R levels were higher in patients with extensive lesions. Serum sIL-2R level showed significant positive correlation with serum C-reactive protein level and erythrocyte sedimentation rate, and significant negative correlation with serum albumin level. In patients with intractable tuberculosis and patients with non-tuberculous mycobacteriosis, serum sIL-2R levels were lower than in patients with new tuberculosis. Even in patients with extensive lesions, serum sIL-2R levels were not elevated. Lower levels of serum sIL-2R, marker of immunocompetent cell activity, suggested that immunocompetent cell activity was suppressed in intractable tuberculosis and in non-tuberculous mycobacteriosis.

Adult↗
PubMed1998

A novel type of myosin encoded by the mouse deafness gene shaker-2.

The mouse recessive deafness mutation, shaker-2(sh-2), represents a plausible model for an autosomal recessive form of human non-syndromic genetic deafness, DFNB3. Here we report the use of a positional cloning approach to show that the gene mutated in sh-2 mice encodes a novel type of unconventional myosin. A G-to-A transition changing cysteine to tyrosine in the conserved actin binding domain is detected in sh-2 but absent in laboratory strains and wild mice belonging to different mouse subspecies and species. This suggests that the novel myosin gene is a strong candidate for DFNB3.

Actins↗
PubMed1998

Identification of alternatively spliced transcripts encoding murine macrophage colony-stimulating factor.

We have isolated a novel cDNA encoding macrophage colony-stimulating factor (M-CSF) from a murine stromal cell line, ST2. The cDNA included an entire coding sequence of the M-CSF gene but contained an additional sequence of 140 base pairs (bp). Northern blot analysis demonstrated that other murine cell lines such as a fibroblastic cell line (L) and a stromal cell line (PA6) also expressed the transcripts corresponding to the clone. The nucleotide sequence analyses of the cDNA and the cloned M-CSF genome revealed that the 140-bp insertion sequence was part of intron 1 which separated exon 1 and exon 2: the former contained part of the amino acid residues of the signal sequence and the latter the rest of the signal sequence and the first 22 amino acid residues of the mature protein. The insertion of the 140-bp intron sequence not only changed the amino acid sequence of the signal peptide but also generated an in-frame termination codon. However, instead of the dysfunction of the original initiation codon, the 140-bp insertion sequence contained a putative ATG initiation codon that preserved the original open reading frame. Finally, we found that the cDNA directed the expression of a secreted and biologically active M-CSF protein when it was introduced into COS7 cells and M-CSF activity in the culture supernatants was measured using an M-CSF-dependent cell line. These results indicate the presence of an alternatively spliced M-CSF transcript which utilizes an alternate initiation codon in order to specify active M-CSF protein.

Alternative Splicing↗