Search PubMed⌕ Search

Biomedical subjects

M Yoshida

Publications and source records attributed to M Yoshida.

At least 541 records · Page 30Linked to original sources
PubMed1999

Identification of a novel Sry-related gene and its germ cell-specific expression.

Sox family proteins are characterized by a unique DNA-binding domain, a HMG box which shows at least 50% sequence similarity with mouse Sry, the sex-determining factor. At present almost 30 Sox genes have been identified. Members of this family have been shown to be conserved during evolution and to play key roles during animal development. Some are involved in human diseases, including sex reversal. Here we report the isolation of a novel member of the Sox gene family, Sox30, which may constitute a distinct subgroup of this family. Using a bacterially expressed DNA-binding domain of Sox30, we show that it is able to specifically recognize the ACAAT motif. Furthermore, Sox30 is capable of activating transcription from a synthetic promoter containing the ACAAT motif. The specific expression of Sox30 in normal testes, but not in maturing germ cell-deficient testes, suggests the involvement of Sox30 in differentiation of male germ cells. Mapping analyses revealed that the Sox30 gene is located on human chromosome 5 (5q33) and on mouse chromosome 11.

Animals↗
PubMed1999

Intrarenal angiotensin converting enzyme inhibition in spontaneously hypertensive rats.

We examined the hypotensive effect of enalapril in relation to the local renin-angiotensin system of the kidney in spontaneously hypertensive rats (SHR). Oral administration of enalapril for 7 days decreased mean arterial blood pressure and renal tissue angiotensin II concentration without affecting plasma angiotensin II concentration in SHR. The enalapril treatment did not affect maximum binding of angiotensin II to renal tubules and glomeruli in SHR. In normotensive Wistar-Kyoto rats, no significant changes in mean arterial blood pressure, renal and plasma angiotensin levels were observed with enalapril treatment. Direct infusion of enalapril into the renal medullary interstitium decreased mean arterial blood pressure in association with the reduction of renal tissue angiotensin II concentration without changes in plasma angiotensin II concentration in SHR. These observations suggest that the inhibition of angiotensin conversion in the kidney is important for the hypotensive action of enalapril.

Administration, Oral↗
PubMed1999

Naturally occurring somatic motoneuron death in a teleost angelfish, Pterophyllum scalare.

Naturally occurring somatic motoneuron death in a teleost angelfish, Pterophyllum scalare, was investigated histochemically and electron microscopically. The number of motor axons in the ventral root, which corresponds to the motoneuron number in spinal hemisegment, was rapidly increased beyond the adult value within 3 days after hatching, and then decreased to reach the adult value within a few weeks. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) histochemistry, which detects fragmented nuclear DNA characteristic to apoptotic cells, showed that the apoptotic cells are located in the motor column of the cord in the larvae at specific developmental stages. Electron microscopic observations of the spinal cells further confirmed the motoneuron apoptosis. The present data suggest that the massive death of somatic motoneurons at certain ontogenic stages which has been known to occur in higher vertebrates also takes place in fish.

Animals↗
PubMed1999

Effects of NKH477 on renal functions and cyclic AMP production in anesthetized dogs.

The present study was undertaken to evaluate the effects of an adenylate cyclase activator N,N-dimethyl-beta-alanine[3R-(3alpha, 4alphabeta, 5beta, 6beta, 6aalpha, 10alpha, 10abeta, 10balpha)]-5(acetyloxy)-3-ethenyldodecahydro-10, 10b-dihydroxy-3, 4a, 7, 7, 10a-pentamethyl-1-oxo-1H-naphtho [2,1-b] pyran-6-yl ester hydrochloride (NKH477) on renal functions and cyclic AMP production in the dog kidney. The intrarenal arterial infusion of NKH477 (30, 100 and 300 ng kg(-1) min(-1)) increased renal blood flow, glomerular filtration rate, urine flow rate, urinary Na+ and cyclic AMP excretion, fractional Na+ excretion and arterial and renal venous plasma cyclic AMP concentrations in a dose-dependent manner. The intrarenal arterial infusion of rolipram (0.3 microg kg(-1) min(-1)), a cyclic AMP-specific phosphodiesterase inhibitor, also caused the same renal responses as NKH477. The increasing effects of NKH477 on renal blood flow, fractional Na+ excretion and renal venous plasma cyclic AMP concentration were facilitated in the presence of rolipram. NKH477 reduced glomerular filtration rate and filtration fraction in the presence of rolipram. The increasing effects of NKH477 on urine flow rate and urinary Na+ excretion were not affected by rolipram. The present results suggest that NKH477 increases glomerular filtration and suppresses tubular sodium reabsorption through activation of cyclic AMP production, and thereby induces natriuresis. The results also demonstrate that renal cyclic AMP level during the activation of adenylate cyclase is regulated by phosphodiesterase IV in both the vascular and tubular sites.

Anesthesia↗
PubMed1999

A novel nuclear export signal sensitive to oxidative stress in the fission yeast transcription factor Pap1.

Pap1, a fission yeast AP-1-like transcription factor, is negatively regulated by CRM1/exportin 1, the nuclear export factor. Pap1 was localized normally in the cytoplasm but was accumulated in the nucleus when Crm1 was inactivated by a temperature-sensitive mutation or by treatment with leptomycin B, a specific export inhibitor. Deletion of the C-terminal cysteine-rich domain (CRD) resulted in nuclear accumulation of Pap1, while a glutathione S-transferase-green fluorescent protein-CRD fusion protein was localized in the cytoplasm in a Crm1-dependent manner. Deletion and mutational analyses identified several important amino acids in a 19-amino acid region in the CRD as a nuclear export signal (NES). Strikingly, a cysteine residue (Cys-532), in addition to two leucines and an isoleucine, was important for the NES function and the presence of at least one of the two cysteine residues was essential. Unlike classical NESs such as the human immunodeficiency virus Rev NES, the Pap1 NES lost the function upon treatment with oxidants such as diethyl maleate. The oxidative stress response is conserved through evolution, as green fluorescent protein-fused proteins bearing the Pap1 NES expressed in mammalian cells responded to diethyl maleate. These results show that the hydrophobic amino acid-rich region containing two important cysteines in Pap1 serves as a novel NES, which is sensitive to oxidative stress.

Amino Acid Sequence↗
PubMed1999

Effects of basic fibroblast growth factor on spontaneous resorption of herniated intervertebral discs. An experimental study in the rabbit.

STUDY DESIGN: Histologic examination was performed on the autologous intervertebral disc material that was removed from the intervertebral space at L1-L2 and then relocated to the L4 posterior epidural space after the addition of basic fibroblast growth factor (bFGF) in a rabbit. OBJECTIVES: To evaluate whether basic fibroblast growth factor influences the resorption process of the herniated intervertebral disc through the promotion of angiogenesis and chemotaxis. SUMMARY OF BACKGROUND DATA: It has been reported that newly formed vessels, inflammatory cells, and their products may play an important role in the spontaneous resorption process of herniated intervertebral discs. In a rabbit model that mimics the sequestration type of intervertebral disc herniation, it has been reported that the autologous intervertebral disc material that relocated into the epidural space was penetrated by newly formed vessels originating from the epidural fat tissue. Therefore, it is possible that promotion of angiogenesis may influence the resorption of herniated intervertebral discs. Basic fibroblast growth factor is well known as an angiogenesis stimulation factor in vivo. METHODS: Thirty-six adult rabbits were divided into three groups. The L1-L2 intervertebral disc was partially incised through a retroperitoneal approach in each rabbit. The harvested disc material, which contained nucleus pulposus and anulus fibrosus, was immersed in one of three kinds of solution before relocation into the posterior epidural space at L4. In the control group, the harvested intervertebral disc was immersed in physiologic saline for 2 hours before relocation. In the group receiving 5 micrograms bFGF, the disc was immersed in 5 micrograms/mL bFGF for 2 hours before the relocation. In the group receiving 20 micrograms bFGF, the disc was immersed in 20 micrograms/mL bFGF for 2 hours before the relocation. Rabbits of each group were killed for histologic examination 1, 2, 4, and 8 weeks after surgery. RESULTS: In the bFGF-treated groups, newly formed vessels were observed to be in more numerous than those in the control group, 1 and 2 weeks after surgery. The number of inflammatory cells, including macrophages, lymphocytes, and fibroblasts, also increased in the bFGF-treated groups. The period from the surgery to the degradation of the intervertebral disc in the bFGF-treated groups was shorter than that in the control group, although the resorption process of the relocated discs was also observed in the control group. The size of relocated intervertebral discs in the bFGF-treated groups decreased at a higher rate than in the control group as time progressed. The rate of decrease in the size of discs in the group treated with 20 micrograms bFGF was more than that in the group treated with 5 micrograms. CONCLUSIONS: Epidural injection of bFGF facilitated the resorption of the intervertebral disc relocated to the epidural space.

Animals↗
PubMed1999

Hepatic uptake of polystyrene microspheres in rats: effect of particle size on intrahepatic distribution.

The in vivo disposition of polystyrene microsphere (MS) with the particle size of 50 nm (MS-50) or 500 nm (MS-500) was characterized after intravenous administration to rats. A rapid elimination from systemic circulation was observed for both MSs. Tissue distribution of MS-50 and MS-500 at 1 h after intravenous injection indicated that both MSs were exclusively distributed to liver and that small but significant amounts of MS-50 and MS-500 were also distributed to lung and spleen, respectively. To investigate the intrahepatic distribution of MS, liver was separated into liver parenchymal cells (PC) and non-parenchymal cells (NPC) at 1 or 6 h after intravenous administration. The contribution of each cell fraction was dependent on both the size of MS and the time after administration. Furthermore, by separating the NPC into endothelial cells and Kupffer cells using a centrifugal elutriation method, their contribution was also evaluated. For both MSs, Kupffer cells were recognized to be mostly responsible for the hepatic uptake, although a significant amount of MS-50 (about 28% of total uptake) was taken up by PC. On the other hand, there was little contribution of PC (about 5%) to the hepatic uptake of MS-500. The endothelial cells were contributed larger to the uptake of MS-500 (about 24%) than that of MS-50 (13%).

Animals↗
PubMed1999

Subzero-temperature liquid-liquid extraction of benzodiazepines for high-performance liquid chromatography.

On the basis of the phenomenon that hydrophilic acetonitrile is separated from the aqueous phase at -20 degrees C, we employed a novel extraction method, "subzero-temperature liquid-liquid extraction", to extract benzodiazepines (estazolam and triazolam) from serum or aqueous solution for liquid chromatography. A 1:1 mixture of acetonitrile and the specimen was cooled at -20 degrees C for 20 min to separate the acetonitrile and aqueous phases. The acetonitrile phase was directly injected into a high-performance liquid chromatograph. Recovery rates of the drugs following the first subzero-temperature liquid-liquid extraction were 50.3 +/- 0.6-54.0 +/- 0.9%, which were lower than those (73.9 +/- 3.3-80.6 +/- 0.6% and 81.6 +/- 4.7-96.1 +/- 2.6%) of the first conventional liquid-liquid extraction using diethyl ether and solid-phase extraction using a Sep-Pak C18 column, respectively. However, three to four repeated subzero-temperature liquid-liquid extractions and conventional liquid-liquid extractions resulted in recovery of almost 100% of the drugs. In the chromatogram of the benzodiazepines recovered from serum by the subzero-temperature extraction, no coextracted component interfered with determination of the drugs. Detection limits of the drugs were 0.02-0.08 microgram/mL, and coefficients of variance were 1.14-2.17% suggesting high reproducibility.

Acetonitriles↗
PubMed1999

Mice with Th2-biased immune systems accept orthotopic corneal allografts placed in "high risk" eyes.

CD4+ T cells of the Th1 type play a central role in acute rejection of solid tissue grafts, including orthotopic corneal allografts. Th1 cells, which mediate delayed hypersensitivity, are the polar opposites of CD4+ Th2 cells, and the latter cells cross-regulate Th1 cells through the unique pattern of cytokines they secrete. As such, Th2 cells may have a useful role to play in preventing rejection of corneal allografts. To test this possibility, the immune systems of adult mice were biased toward Th2 responses by immunization with keyhole limpet hemocyanin plus IFA. When immunized subsequently with either OVA or allogeneic corneal tissue, these mice acquired Ag-specific primed T cells of the Th2 type. More important, allogeneic corneas grafted into neovascularized eyes of Th2-biased mice experienced significantly enhanced survival. To demonstrate that enhanced survival was promoted by donor-specific Th2 cells, lymphoid cells from keyhole limpet hemocyanin-immune mice bearing healthy corneal allografts suppressed orthotopic corneal allograft rejection when adoptively transferred into naive, syngeneic recipients. We conclude that acceptance of corneal allografts in neovascularized mouse eyes can be significantly enhanced by biasing the recipient immune system toward Th2 responses.

Adoptive Transfer↗
PubMed1999

MCP-1 and IL-8 trigger firm adhesion of monocytes to vascular endothelium under flow conditions.

Monocytes contribute to the development of atherosclerotic lesions in mouse models. The chemoattractant proteins (chemokines), monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8), are found in human atheroma, and mice lacking receptors for these chemokines are less susceptible to atherosclerosis and have fewer monocytes in vascular lesions. Although MCP-1 has a powerful effect on monocytes, IL-8 is thought to act predominantly on neutrophils and it is unclear how it could recruit monocytes. Here we investigate the ability of chemokines to control the interaction of monocytes under flow conditions with vascular endothelium that has been transduced to express specific leukocyte-adherence receptors. We find that MCP-1 and IL-8 can each rapidly cause rolling monocytes to adhere firmly onto monolayers expressing E-selectin, whereas related chemokines do not. These effects do not correlate with either the induction of a calcium transient or chemotaxis. We conclude that chemokines are important modulators of monocyte-endothelial interactions under flow conditions. Moreover, our finding that IL-8 is a powerful trigger for firm adhesion of monocytes to vascular endothelium reveals an unexpected role for this chemokine in monocyte recruitment.

Cell Adhesion↗
PubMed1999

A new cytochrome subunit bound to the photosynthetic reaction center in the purple bacterium, Rhodovulum sulfidophilum.

The nucleotide sequence of the puf operon, which contains the genes encoding the B870 light-harvesting protein and the reaction center complex of the purple photosynthetic bacterium, Rhodovulum sulfidophilum, was determined. The operon, which consisted of six genes, pufQ, pufB, pufA, pufL, pufM, and pufC, is a new variety in photosynthetic bacteria in the sense that pufQ and pufC coexist. The amino acid sequence of the cytochrome subunit of the reaction center deduced from the pufC sequence revealed that this cytochrome contains only three possible heme-binding motifs; the heme-1-binding motif of the corresponding tetraheme cytochrome subunits was not present. This is the first exception of the "tetraheme" cytochrome family in purple bacteria and green filamentous bacteria. The pufC sequence also revealed that the sixth axial ligands to heme-1 and heme-2 irons were not present in the cytochrome either. This cytochrome was actually detected in membrane preparation as a 43-kDa protein and shown to associate functionally with the photosynthetic reaction center as the immediate electron donor to the photo-oxidized special pair of bacteriochlorophyll. This new cytochrome should be useful for studies on the role of each heme in the cytochrome subunit of the bacterial reaction center and the evolution of proteins in photosynthetic electron transfer systems.

Amino Acid Sequence↗
PubMed1999

Oxamflatin is a novel antitumor compound that inhibits mammalian histone deacetylase.

Oxamflatin [(2E)-5-[3-[(phenylsufonyl) aminol phenyl]-pent-2-en-4-ynohydroxamic acid] induces transcriptional activation of junD and morphological reversion in various NIH3T3-derived transformed cell lines. We found that oxamflatin showed in vitro antiproliferative activity against various mouse and human tumor cell lines with drastic changes in the cell morphology and in vivo antitumor activity against B16 melanoma. Oxamflatin caused an elongated cell shape with filamentous protrusions as well as arrest of the cell cycle at the G1 phase in HeLa cells. These phenotypic changes of HeLa cells were apparently similar to those by trichostatin A (TSA), a specific inhibitor of histone deacetylase (HDAC). The effect of oxamflatin on the transcriptional activity of the cytomegalovirus (CMV) promoter was examined and compared with known HDAC inhibitors, TSA, sodium n-butyrate, and FR901228. Oxamflatin as well as all these inhibitors greatly enhanced the transcriptional activity of the CMV promoter in a dose-dependent manner. Oxamflatin, like TSA, inhibited intracellular HDAC activity, as a result of which marked amounts of acetylated histone species accumulated. Finally, effects on expression of several endogenous genes involved in cell morphology and cell cycle control in HeLa cells were analysed. Expression of gelsolin, cyclin E and Cdk inhibitors including p21WAF1/Cip1 was highly augmented, while that of cyclin A and cyclin D1 was decreased by oxamflatin. These results suggest that changes in the expression pattern of the genes regulating cell morphology and the cell cycle due to histone hyperacetylation are responsible for the antitumor activity, the morphological change and the cell cycle arrest induced by oxamflatin.

Animals↗
PubMed1999

Maintenance of G2 arrest in the Xenopus oocyte: a role for 14-3-3-mediated inhibition of Cdc25 nuclear import.

Cdc2-cyclin B1 in the G2-arrested Xenopus oocyte is held inactive by phosphorylation of Cdc2 at two negative regulatory sites, Thr14 and Tyr15. Upon treatment with progesterone, these sites are dephosphorylated by the dual specificity phosphatase, Cdc25, leading to Cdc2-cyclin B1 activation. Whereas maintenance of the G2 arrest depends upon preventing Cdc25-induced Cdc2 dephosphorylation, the mechanisms responsible for keeping Cdc25 in check in these cells have not yet been described. Here we report that Cdc25 in the G2-arrested oocyte is bound to 14-3-3 proteins and that progesterone treatment abrogates this binding. We demonstrate that Cdc25, apparently statically localized in the cytoplasm, is actually capable of shuttling in and out of the oocyte nucleus. Binding of 14-3-3 protein markedly reduces the nuclear import rate of Cdc25, allowing nuclear export mediated by a nuclear export sequence present in the N-terminus of Cdc25 to predominate. If 14-3-3 binding to Cdc25 is prevented while nuclear export is inhibited, the coordinate nuclear accumulation of Cdc25 and Cdc2-cyclin B1 facilitates their mutual activation, thereby promoting oocyte maturation.

14-3-3 Proteins↗
PubMed1999

Soluble interleukin-6 (IL-6) receptor with IL-6 stimulates megakaryopoiesis from human CD34(+) cells through glycoprotein (gp)130 signaling.

We have recently shown that stimulation of glycoprotein (gp) 130, the membrane-anchored signal transducing receptor component of IL-6, by a complex of human soluble interleukin-6 receptor (sIL-6R) and IL-6 (sIL-6R/IL-6), potently stimulates the ex vivo expansion as well as erythropoiesis of human stem/progenitor cells in the presence of stem cell factor (SCF). Here we show that sIL-6R dose-dependently enhanced the generation of megakaryocytes (Mks) (IIbIIIa-positive cells) from human CD34(+) cells in serum-free suspension culture supplemented with IL-6 and SCF. The sIL-6R/IL-6 complex also synergistically acted with IL-3 and thrombopoietin (TPO) on the generation of Mks from CD34(+) cells, whereas the synergy of IL-6 alone with TPO was barely detectable. Accordingly, the addition of sIL-6R to the combination of SCF + IL-6 also supported a substantial number of Mk colonies from CD34(+) cells in serum-free methylcellulose culture, whereas SCF + IL-6 in the absence of sIL-6R rarely induced Mk colonies. The addition of monoclonal antibodies against gp130 to the suspension and clonal cultures completely abrogated the megakaryopoiesis induced by sIL-6R/IL-6 in the presence of SCF, whereas an anti-TPO antibody did not, indicating that the observed megakaryopoiesis by sIL-6R/IL-6 is a response to gp130 signaling and independent of TPO. Furthermore, human CD34(+) cells were subfractionated into two populations of IL-6R-negative (CD34(+) IL-6R-) and IL-6R-positive (CD34(+) IL-6R+) cells by fluorescence-activated cell sorting. The CD34(+) IL-6R- cells produced a number of Mks as well as Mk colonies in cultures supplemented with sIL-6R/IL-6 or TPO in the presence of SCF. In contrast, CD34(+) IL-6R+ cells generated much less Mks and lacked Mk colony forming activity under the same conditions. Collectively, the present results indicate that most of the human Mk progenitors do not express IL-6R, and that sIL-6R confers the responsiveness of human Mk progenitors to IL-6. Together with the presence of functional sIL-6R in human serum and relative unresponsiveness of human Mk progenitors to IL-6 in vitro, current results suggest that the role of IL-6 may be mainly mediated by sIL-6R, and that the gp130 signaling initiated by the sIL-6R/ IL-6 complex is involved in human megakaryopoiesis in vivo.

Antigens, CD↗
PubMed1999

Sequences downstream of the RNA initiation site of the HTLV type I long terminal repeat are sufficient for trans-activation by human cytomegalovirus immediate-early proteins.

Human T cell leukemia virus type I infection is associated with a low incidence of morbidity in the form of adult T cell leukemia and neurologic disease, suggesting that there are other factors determining the pathogenic outcome of infection. We found that HCMV could infect various human cell lines known to be susceptible to HTLV-I infection, including T cell lines already harboring HTLV-I, and that HCMV infection could highly activate gene expression from the HTLV-I LTR. In addition, the coexpression of IE1 and IE2 genes of HCMV increased transcription from the HTLV-I LTR. The deletion analysis indicated that the entire U3 region is not required, but that the 216-bp region from +101 to +316 is sufficient for activation of the LTR by IE1 and IE2. These results suggest that HCMV IE proteins may affect the level of HTLV-I gene expression in coinfected individuals by interacting with HTLV-I LTR sequences.

Antigens, Viral↗
PubMed1999

Effect of high-density extremely low frequency magnetic field on sister chromatid exchanges in mouse m5S cells.

The induction of sister chromatid exchanges (SCEs) was evaluated in the cultured mouse m5S cells after exposure to extremely low frequency magnetic field (ELFMF; 5, 50 and 400 mT). Exposure to 5 mT and 50 mT ELFMF led to a very small increase in the frequency of SCEs, but no significant difference was observed between exposed and unexposed control cells. The cells exposed to 400 mT ELFMF exhibited a significant elevation of the SCE frequencies. There was no significant difference between data from treatments with mitomycin-C (MMC) alone and from combined treatments of MMC plus ELFMF (400 mT) at any MMC concentrations from 4 to 40 nM. These results suggest that exposure to highest-density ELFMF of 400 mT may induce DNA damage, resulting in an elevation of the SCE frequencies. We suppose that there may be a threshold for the elevation of the SCE frequencies, that is at least over the magnetic density of 50 mT.

Animals↗
PubMed1999

Oncogenic Ras triggers cell suicide through the activation of a caspase-independent cell death program in human cancer cells.

To prevent neoplasia, cells of multicellular organisms activate cellular disposal programs such as apoptosis in response to deregulated oncogene expression, making the suppression of such programs an essential step for potentially neoplastic cells to become established as clinically relevant tumors. Since the mutation of ras proto-oncogenes, the most frequently mutated proto-oncogenes in human tumors, is very rare in some tumor types such as glioblastomas and gastric cancers, we hypothesized that mutated ras genes might activate a cell death program that cannot be overcome by these tumor types. Here we show that the expression of oncogenically mutated ras gene induces cellular degeneration accompanied by cytoplasmic vacuoles in human glioma and gastric cancer cell lines. Cells dying as a result of oncogenic Ras expression had relatively well-preserved nuclei that were negative for TUNEL staining. An immunocytochemical analysis demonstrated that the cytoplasmic vacuoles are derived mainly from lysosomes. This oncogenic Ras-induced cell death occurred in the absence of caspase activation, and was not inhibited by the overexpression of anti-apoptotic Bcl-2 protein. These observations suggested that oncogenic Ras-induced cell death is most consistent with a type of programmed cell death designated 'type 2 physiological cell death' or 'autophagic degeneration', and that this cell death is regulated by a molecular mechanism distinct from that of apoptosis. Our findings suggest a possible role for this non-apoptotic cell death in the prevention of neoplasia, and the activation of the non-apoptotic cell death program may become a potential cancer therapy complementing apoptosis-based therapies. In addition, the approach used in this study may be a valuable way to find genetically-regulated cell suicide programs that cannot be overcome by particular tumor types.

Brain Neoplasms↗