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T Semba

Publications and source records attributed to T Semba.

At least 19 recordsLinked to original sources
PubMed1999

Establishment of a quantitative mouse dorsal air sac model and its application to evaluate a new angiogenesis inhibitor.

We have developed an improved mouse dorsal air sac model for quantifying in vivo tumor-induced angiogenesis. In our improved model, tumor angiogenesis is determined by measuring the blood volume in an area of skin held in contact with a tumor cell-containing chamber, using 51Cr-labeled red blood cells (RBC). The blood volume induced by murine B16-BL6 melanoma cells increased linearly with the cell number in the range from 2 x 10(5) to 5 x 10(6). Ten of 11 human tumor cell lines examined induced a significant increment in blood volume. For three representative human tumor cell lines (A549, WiDr. and HT1080 cells) that showed different angiogenic potencies, the levels of vascular endothelial growth factor (VEGF) produced by the tumor cells cultured under conditions of hypoxia and high cell density were correlated with the degree of in vivo angiogenesis. Using the improved model, it was confirmed that TNP-470, a well-known inhibitor, and borrelidin, an antibiotic from Streptomyces rochei, significantly inhibited the WiDr cell-induced angiogenesis. Borrelidin also inhibited spontaneous lung metastasis of B16-BL6 melanoma at the same dose that inhibited angiogenesis. Our results suggest that the improved mouse dorsal air sac model can be used for simple and quantitative measurement of tumor-induced angiogenesis and its inhibition.

Angiogenesis Inhibitors↗
PubMed1996

Pediatric brain stem gliomas with the predominant symptom of sleep apnea.

Two children complaining of sleep apnea presented with brain stem gliomas. In the early stage of their illness, neurological disorders were too subtle to be recognized as significant by the physicians or to be noted by the parents. Case 1 experienced an episode of unsteady gait and weakness in the bilateral arms, at the age of 5. When it recurred after 7 years of remission, the predominant symptom was sleep apnea. Case 2 exhibited nasality of speech as the earliest sign of this illness very early in his life, presumably 5 years before the diagnosis of brain stem glioma. A slight sleep apnea which developed afterwards did not draw attention of the physicians because no neurological signs other than paralyses of the bilateral soft palates were present. MRIs of the both cases revealed diffuse, infiltrating lesions in the pons, the medulla oblongata and the upper cervical spinal cord. Both cases shared some features: (1) diagnostic delay of several years from the first symptom; (2) the main lesion in the medulla oblongata, where important structures for respiratory control are identified; (3) infiltrative growth patterns in the MRI of the tumor, which might account for the uncommon clinical courses.

Blood Gas Analysis↗
PubMed1995

High expression of membrane cofactor protein of complement (CD46) in human leukaemia cell lines: implication of an alternatively spliced form containing the STA domain in CD46 up-regulation.

Human membrane cofactor protein (MCP, CD46) is a receptor for the measles virus and serves as a complement regulator which protects host cells from autologous complement attack. MCP is highly polymorphic due to a variety of mRNA splice products. The levels of MCP expression on T and myeloid cell lines are usually two-eightfold higher than those on their normal counterparts, whereas Burkitt's lymphoma B cell lines express less MCP than B cell lineages carrying no EB virus. The molecule has a Ser/Thr-rich (ST) domain adjacent to the functional domain, namely short consensus repeats (SCR). The ST domain and a cytoplasmic tail (CYT) contribute to the MCP polymorphism. The ST domain is encoded by three exons (A, B and C) and major ST isoforms are STABC, STBC and STC. The authors investigated the relationship between the expression levels and isoform usage of MCP by flow cytometry using specific antibodies against STA and STC, by reverse transcriptase-polymerase chain reaction (RT-PCR) with size markers for each splice variant, and by RT-PCR/Southern blotting using a specific probe for STA. The results were (1) the profiles of mean shifts of myeloid and T cell lines were STC < STA on flow cytometry while those of B cell lines and normal blood cells were STA < STC; (2) all cell lines tested by RT-PCR expressed the messages for the isoforms STBC/CYT1, STC/CYT1, STBC/CYT2, and STC/CYT2. The band for STABC/CYT2 overlapped that for STC/CYT1, and the band for STABC/CYT1 was marginal in all cell lines examined; (3) semi-quantitative analysis of the STABC isoforms by Southern blotting indicated the presence of high levels of the STABC messages in myeloid and T-cell lines in comparison with B lymphoid cells and normal leucocytes. Thus, the quantity of MCP expressed parallels the STABC message level, which is up-regulated in T and myeloid leukaemia cell lines.

Alternative Splicing↗
PubMed1995

Blocking measles virus infection with a recombinant soluble form of, or monoclonal antibodies against, membrane cofactor protein of complement (CD46).

Human membrane cofactor protein (MCP, CD46) functions as an inhibitor of the complement (C) cascade to protect host cells from C attack, and as a receptor for measles virus (MV). Normal human sera contains 10-60 ng/ml of naturally produced soluble forms of MCP, which is also a cofactor for the factor I-mediated inactivation of C3b. We produced monoclonal antibodies (mAb) against MCP and a recombinant soluble form of MCP similar to the natural soluble forms, and tested their ability to block MV infection. Vero cells and CHO cells expressing human MCP were the targets. Of the antibodies tested, M75 and M177, which blocked the C regulatory activity of MCP, efficiently blocked MV infection. More than 50 micrograms/ml of the soluble form moderately blocked MV infection of CHO cells expressing MCP, but barely blocked that of Vero cells. The two mAb and the soluble form also inhibited MV H protein-mediated green monkey erythrocyte rosette formation. A quantitative analysis suggested that 30 micrograms/ml of the soluble form functionally corresponded to 0.2 microgram/ml of M177 or M75. These data established that the C regulatory function and the MV receptor function of MCP were blocked simultaneously by the individual mAb, and that soluble forms of MCP could inhibit MV infection in cells expressing human MCP, although doses far higher than the natural concentration of soluble MCP were required.

Animals↗
PubMed1994

Human alpha-galactosidase gene expression: significance of two peptide regions encoded by exons 1-2 and 6.

Two proteins with alpha-galactosidase activity, alpha-galactosidase A (alpha-GalA) and alpha-galactosidase B (alpha-GalB, or alpha-N-acetylgalactosaminidase; alpha-NAGA) have a high homology of amino-acid sequence. Point mutations of the alpha-GalA gene have been reported only in the exons 1, 2 or 6. In this study, the exon 1-2 and/or 6 sequences of alpha-GalA cDNA were partly substituted by the corresponding regions of alpha-GalB cDNA, and three chimeric proteins were prepared by the baculovirus expression system: CMB12 with substitution at the exon 1-2 region, CMB6 at the exon 6 region, and CMB126 at both regions. They all preserved alpha-GalA antigenicity. Their kinetic properties toward 4-methylumbelliferyl alpha-galactopyranoside were compared with those of alpha-GalA. The catalytic activity was slightly low in CMB12, decreased to 1/10 in CMB6, and restored to a significant degree in CMB126. Km was more than 4-fold higher for CMB6 and CMB126 than for alpha-GalA. The pH optimum was 4.0 for both CMB12 and alpha-GalA, 4.8 for CMB6, and 4.6 for CMB126 and alpha-GalB. The catalytic activity was inhibited most by galactosamine in CMB6, and less in alpha-GalB, CMB126, alpha-GalA and CMB12 in decreasing order. The 50% inhibition concentrations of melibiose (Gal alpha 1-6Glc) and methyl alpha-galactopyranoside were 2.5- to 3-fold higher for CMB126 than for alpha-GalA. These results indicate that the low affinity of CMB126 to the substrate was caused by a reduced affinity to terminal alpha-linked galactose. We conclude that (1) the two regions encoded by exons 1-2 and 6 contribute to the alpha-galactosidic cleavage, and (2) an increase in Km of CMB6 or CMB126, with chimeric substitutions at the exon 6 region, was caused by a loss of affinity toward terminal alpha-linked galactose.

Amidohydrolases↗
PubMed1994

Genetic polymorphisms of the CST2 locus coding for cystatin SA.

A new genetic polymorphism of cystatin SA has been identified in human submandibular-sublingual saliva by means of basic gel electrophoresis and immunoblotting with anti-cystatin S. Two proteins, SA1 and SA2, are given by two alleles of CST2, viz., CST2*1 and CST*2. Inheritance is controlled by two codominant alleles at an autosomal locus. This hypothesis is supported by studies of 16 families 32 children. Gene frequencies for CST2*1 and CST2*2 are 0.935 and 0.065, respectively (n = 341). Eighteen amino acids determined among 20 N-terminal residues of cystatin SA2 are identical with the sequence encoded by CST2. Three forms of cystatin S (mono-phosphorylated cystatin S, di-phosphorylated cystatin S, and non-phosphorylated cystatin S) are present in the 341 saliva samples tested.

Amino Acid Sequence↗
PubMed1994

Studies on thermophile products. IX. Isofatty acid-containing phosphatidylglycerol that enhances the induction of concanavalin A-activated suppressor T cells.

A new enhancer of the induction of concanavalin A (Con A)-activated suppressor T (Ts) cells has been demonstrated in the ethanolysate of Bacillus stearothermophilus UBT8038. It was purified by successive silica gel column chromatographies and identified as phosphatidylglycerol with C14:0-C18:0 isofatty acids (Fr. 7-C). Mouse splenocytes activated with Con A and Fr. 7-C (0.01-1 microgram/ml) in vitro significantly suppressed the proliferative response of syngenic splenocytes by mitogen stimulation in a dose-dependent manner, compared to those stimulated by Con A alone. The immunosuppressive response enhanced by Fr. 7-C disappeared when the cell populations of Thy-1.2 or CD8 positive lymphocytes were depleted. The result strongly suggests that Fr. 7-C is an immunosuppressive substance which enhances the induction of Con A-activated CD8 positive Ts cells.

Animals↗
PubMed1994

Studies on thermophile products. X. Further biological properties of isofatty acid-containing phosphatidylglycerol that enhances the induction of suppressor T cells.

Isofatty acid-containing phosphatidylglycerol (Fr. 7-C), isolated from Bacillus stearothermophilus UBT8038, enhances the induction of concanavalin A (Con A)-activated suppressor T (Ts) cells in a dose dependent manner (0.01-1 microgram/ml). Its further biological properties on mouse mixed lymphocyte reaction (MLR) has been demonstrated. Fr. 7-C (0.01-1 microgram/ml) suppressed the MLR at 4 d in a dose-dependent manner when added at the start of splenocyte cultivation. Moreover, Fr. 7-C was effective in preventing the generation of cytotoxic T lymphocytes after the MLR. On the other hand, this fraction significantly enhanced the induction of Ts cells in the MLR carried out in any of the antigen-specific, antigen-nonspecific and major histocompatibility complex antigen-nonrestricted fashions. Fr. 7-C increased prostaglandin E2 (PGE2) release approximately 2-fold in the culture supernatant of Con A-activated splenocytes, and PGE2 release decreased dose-dependently when cultured with indomethacin. The inhibitory effect by Fr. 7-C on the MLR was abrogated by the addition of indomethacin. The enhancement by Fr. 7-C on Ts cell induction was blocked by indomethacin in a dose dependent manner. These results strongly suggest that Fr. 7-C suppresses the MLR via the enhancement of antigen-nonspecific Ts cell induction mediated at least partly by PGE2.

Animals↗
PubMed1994

Studies on thermophile products. VII. Effect of 1,3-di-14-methylpentadecanoyl glycerol and its related isofatty acids on T cell proliferation in vitro.

It has been found that Bacillus stearothermophilus UK563-derived immunosuppressant fraction (Fr. 5-B) consists of 1,3-diacylglycerols with saturated iso- and anteiso-type fatty acids (C14:0-C18:0) as major components. The compound, 1,3-di-14-methylpentadecanoyl glycerol (1,3-diiso C16:0 G), was synthesized and its effect on T cell proliferation was investigated together with its related isofatty acids. While 1,3-diiso C16:0 G, iso C16:0, iso C17:0, iso C17:0 methyl ester (OMe) and anteiso C17:0 OMe suppressed the mixed lymphocyte reaction (MLR) of C57BL/6 against BALB/c mice, iso C15:0, 1,3-acylglycerols with normal C16:0, C16:1 and C18:0 did not, suggesting that the presence of isofatty acids with a certain length may be essential for the suppression of MLR. 1,3-Diiso C16:0 G and iso C16:0 strongly inhibited the autologous MLR of mesenteric lymph node cells against self-antigen presenting cells in MRL/MpJ-lpr/lpr (MRL/lpr) mice, but had no effect on concavalin A-induced T cell proliferation.

Animals↗
PubMed1994

Hyperphosphorylation of a novel 80 kDa protein-tyrosine kinase similar to Ltk in a human Ki-1 lymphoma cell line, AMS3.

Ki-1 lymphoma is a subtype of human malignant lymphoma characterized by the expression of CD30 (Ki-1) and a peculiar morphology. It is occasionally accompanied by a unique reciprocal chromosomal translocation t(2;5)(p23;q35). A Ki-1 lymphoma cell line, AMS3, was established by maintaining biopsied tumor cells in SCID (severe combined immunodeficiency) mice. To investigate abnormalities of the signal transduction in Ki-1 lymphomas, AMS3 lysate was immunoprecipitated with anti-phosphotyrosine monoclonal antibody, 25.2G4, and the immunoprecipitates were subjected to kinase assay and immuno-blotting with 25.2G4. A unique phosphotyrosine-containing protein of MW 80,000, designated p80, was found only in AMS3 cells and not in other cell lines or mononuclear cells from healthy donors. Subsequent amino acid sequence analysis of its tryptic digests showed that p80 was a hitherto undescribed tyrosine phosphoprotein similar to Ltk (leukocyte tyrosine kinase). Furthermore, physical interaction of p80 with CD30 was suggested from immunoprecipitation experiments with AMS3 lysates.

Animals↗
PubMed1993

Tumor necrosis factor-alpha induces expression of monocyte chemoattractant JE via fos and jun genes in clonal osteoblastic MC3T3-E1 cells.

The mechanism by which circulating monocytes are attracted to sites of bone remodeling is unknown. We now report that tumor necrosis factor-alpha (TNF-alpha), a potent osteotrophic cytokine, was stimulatory for expression of the monocyte chemoattractant JE gene in osteoblastic MC3T3-E1 cells. TNF-alpha stimulated this JE gene expression transcriptionally. The presence of JE gene product in conditioned medium of the cytokine-treated cells was evidenced by an immunoprecipitation assay with antiserum specific for JE/MCP-1. The stimulated JE gene expression was markedly inhibited by H-7, a potent inhibitor of protein kinase C. Phorbol 12-myristate 13-acetate induced the JE gene expression, and the cytokine-induced JE gene expression was down-regulated by the phorbol ester pretreatment. TNF-alpha induced expression of both early protooncogenes, c-fos and c-jun, in the cells. Antisense oligonucleotides to these oncogenes significantly inhibited the cytokine-induced monocyte chemotactic activity. Furthermore, curcumin, a specific inhibitor of c-jun/AP-1, markedly inhibited JE gene expression and monocyte chemotactic activity induced by the cytokine. These results suggest that TNF-alpha may contribute to the regulation of remodeling and inflammation of bone tissues through the JE gene product.

3T3 Cells↗
PubMed1993

Identification of HS1 protein as a major substrate of protein-tyrosine kinase(s) upon B-cell antigen receptor-mediated signaling.

Crosslinking of membrane-bound immunoglobulins, which are B-cell antigen receptors, causes proliferation and differentiation of B cells or inhibition of their growth. The receptor-mediated signaling involves tyrosine phosphorylation of cellular proteins and rapid activation of Src-like kinases. The amino acid sequences of five proteolytic peptides of p75, a major substrate of protein-tyrosine(s) in the signaling, showed that p75 is the human HS1 gene product. The HS1 gene is expressed specifically in hematopoietic cells and encodes p75HS1, which carries both helix-turn-helix and Src homology 3 motifs. p75HS1 showed rapid tyrosine phosphorylation and association with a Src-like kinase, Lyn, after crosslinking of membrane-bound IgM. Thus, p75HS1 may be an important substrate of Lyn and possibly other protein-tyrosine kinases upon B-cell antigen receptor-mediated signaling.

Adaptor Proteins, Signal Transducing↗
PubMed1993

Fate of odontoblasts and blood capillaries in the incisal region of the rat incisor pulp.

Transmission electron microscopy of thin sections of the rat incisor pulp revealed that in the middle region of the incisor there were fenestrated capillaries in the "predentinal plexus" and that this region contained the tallest odontoblasts. The odontoblasts gradually became shortened in the incisal part of this region; the fenestrated capillaries in the predentinal plexus changed to continuous type capillaries. Almost all the odontoblasts had degenerated near the incisal end of the tooth. The predentinal plexus disappeared in this region, but the "subodontoblastic capillary plexus" persisted. In a specific region just beneath the worn incisal end, numerous macrophages and polymorphonuclear neutrophils appeared and scavenged the degenerating cells, possibly including the odontoblasts.

Animals↗
PubMed1993

Studies on thermophile products. VI. Activation of mouse peritoneal macrophages by bis(2-hydroxyethyl) trisulfide.

The biological effects of a cytotoxic substance (BS-1), isolated from Bacillus stearothermophilus UK563 and identified as bis(2-hydroxyethyl) trisulfide, on elicited mouse peritoneal macrophages induced by a casein injection, were investigated in vitro. BALB/c mouse macrophages treated or pretreated with BS-1 (1-10 micrograms/ml) showed cytotoxicity against syngeneic DBA/2 mouse P815 mastocytoma. BS-1 also showed weak cytotoxicity directly against P815 in the absence of macrophages. BS-1 significantly increased the glucose consumption of macrophages without producing cytotoxicity. This trisulfide compound increased nitric oxide formation, interleukin-1 production and prostaglandin E2 release in macrophages. It did not, however, increase the production of active oxygen species in macrophages, but it reduced cytochrome c in the presence of phagocytes. These results indicate that BS-1 activates macrophages to the cytolytic stage.

Animals↗
PubMed1992

A long synthetic peptide containing a nuclear localization signal and its flanking sequences of SV40 T-antigen directs the transport of IgM into the nucleus efficiently.

Synthetic short peptides containing only the nuclear localization signal (NLS) direct the transport of nonnuclear proteins into the nucleus. As a conjugate of the synthetic peptide with immunoglobulin M (IgM) did not enter the nucleus, there was believed to be a size limit for nuclear transport of NLS-conjugated proteins. However, we found that IgM conjugated with purified nucleoplasmin, a nuclear protein of Xenopus oocytes, rapidly accumulated in the nucleus. For direct comparison with the short peptide, we prepared a long peptide containing the NLS and its flanking sequences of SV40 large T-antigen and its mutated long peptide, in which possible phosphorylation sites located at the amino terminal of the NLS were changed to alanine. Kinetic experiments showed that wild-type long peptide-IgM conjugates were almost entirely taken up into the nucleus within 30 min after their injection, whereas almost 60 min was required for the mutated long peptide-IgM conjugates to enter the nucleus of all the cells examined, and there was no apparent accumulation of short peptide-IgM conjugates in the nucleus within 60 min. These results indicate that even when the kinetics of transport are affected by amino acid substitutions, the long peptide directs the transport of large molecules such as IgM into the nucleus.

Amino Acid Sequence↗
PubMed1992

Studies on thermophile products. IV. Structural elucidation of cytotoxic substance, BS-1, derived from Bacillus stearothermophilus.

A new cytotoxic substance designated as BS-1 was isolated from the autolysate and culture filtrate of Bacillus stearothermophilus UK563. On the basis of spectral data, the structure of BS-1 was determined as bis(2-hydroxyethyl) trisulfide and confirmed by direct comparison with the synthetic compound. BS-1 exhibited potent cytotoxicity against leukemia P388-D1, leukemia P388, mastocytoma P815, lymphoma EL4 and lymphoma MOLT4.

Antineoplastic Agents↗
PubMed1991

Isolation of a new antitumor substance from Bacillus stearothermophilus.

A new antitumor substance, BS-1, was isolated from the autolysate and culture filtrate of Bacillus stearothermophilus UK563 by ethylacetate extraction and HPLC. BS-1 inhibited the proliferation of mouse macrophage-like cells, P388-D1 (IC50: 4 micrograms/ml) and mouse mastocytoma, P-815 (IC50: 0.6 microgram/ml), but not that of Balb/c 3T3.

Animals↗