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S Ishii

Publications and source records attributed to S Ishii.

At least 55 records · Page 3Linked to original sources
PubMed2001

Mechanosensitive afferent units in the lumbar posterior longitudinal ligament.

STUDY DESIGN: The mechanosensitive afferent units in the lumbar posterior longitudinal ligament were investigated in an animal model using an electrophysiologic technique. OBJECTIVES: The objectives of this study were to identify the mechanosensitive receptive fields in the lumbar posterior longitudinal ligament and to investigate their distribution and characteristics. SUMMARY OF BACKGROUND DATA: The lumbar posterior longitudinal ligament has a nerve network originating from the sinuvertebral nerve. These fibers are thin, and most of their terminals are free nerve endings. Some immunohistochemical studies have indicated that they are immunoreactive to calcitonin gene-related peptide and/or substance P, suggesting a nociceptive function. Most of these studies investigated morphologic aspects, and there have been few studies employing electrophysiologic techniques to examine mechanosensitive units. METHODS: We used 13 adult cats. They were anesthetized and then laminectomy was performed. The L5 and L6 dorsal rootlets were draped over a recording electrode. To investigate the receptive fields in the posterior longitudinal ligament, afferent impulses were evoked by mechanical stimulation with a glass probe. When the receptive fields were located, they were stimulated electrically to obtain conduction velocity and were stimulated with a set of 17 nylon filaments to determine their mechanical thresholds. RESULTS: Thirteen units were identified in the lumbar posterior longitudinal ligament. The majority of the units were located around the intervertebral disc level of the posterior longitudinal ligament. The mean mechanical threshold was 47.04 +/- 15.25 g. According to the conduction velocities of the units, 12 units were classified into Group III (0.5-2.5 m/sec) and one unit into Group IV (2.5-20 m/sec). CONCLUSION: Mechanosensitive units classified into Group III or Group IV and with a high mechanical threshold (>7.0 g) were thought to act as nociceptive units. All units identified in this study satisfied these criteria. Our result suggests that afferent fibers from the lumbar posterior longitudinal ligament have a principally nociceptive function.

Afferent Pathways↗
PubMed2001

The Ski protein family is required for MeCP2-mediated transcriptional repression.

DNA methylation is essential for development in the mouse and plays an important role in inactivation of the X chromosome and genomic imprinting. MeCP2 is the founder member of a family of methyl-CpG-binding proteins. MeCP2 directly binds to the co-repressor mSin3, which interacts with class I histone deacetylase, recruiting them to methyl-CpG regions to suppress transcription. Here, we report that MeCP2 directly binds to two co-repressors, c-Ski and N-CoR, in addition to mSin3A, and that the c-Ski, which is encoded by the c-ski proto-onocogene, is required for MeCP2-mediated transcriptional repression. The two regions of c-Ski, including the C-terminal coiled-coil region, interact with the transcriptional repression domain in the center of the MeCP2 molecule. The immunostaining signals for c-Ski and MeCP2 overlap in the nuclear heterochromatin region, suggesting the co-localization of the two proteins. The degree of transcriptional repression mediated by a Gal4-MeCP2 fusion protein was abrogated by overexpression of the putative dominant negative form of c-Ski. Furthermore, injection of antibodies against c-Ski and Sno almost completely abolished the transcriptional repression mediated by the Gal4-MeCP2 fusion protein. These results suggest that the ski gene family is involved in methyl CpG-mediated transcriptional repression.

Blotting, Western↗
PubMed2001

Intramolecular C-H insertion reactions of (eta(5)-cyclopentadienyl)dicarbonyliron carbene complexes: scope of the reactions and application to the synthesis of (+/-)-sterpurene and (+/-)-pentalenene.

(eta(5)-Cyclopentadienyl)dicarbonyliron carbene complexes, [(eta(5)-C(5)H(5))(CO)(2)Fe=CHR](+)BF(4)(-), are generated as reactive intermediates from thioether derivatives, (eta(5)-C(5)H(5))(CO)(2)FeCH(R)SPh, by S-alkylation with trimethyloxonium tetrafluoroborate and loss of thioanisole. The carbene complexes undergo intramolecular C-H insertion into appropriately situated side chains to form cyclopentane derivatives. The reaction has been developed into a general procedure employing cycloalkanones as scaffolds bearing the iron carbene moieties and the side chains at C(2) and C(3), respectively. The products of the intramolecular insertion reactions are substituted bicyclo[n.3.0]alkanones. The scope and limitations of the reaction are described. The reaction is applied to a total synthesis of sterpurene and to a formal synthesis of pentalenene. Overall, this approach to cyclopentane annulation complements the related metal-catalyzed insertion reactions of diazocarbonyl compounds, which are also believed to occur via metal carbene complexes.

Cyclopentanes↗
PubMed2001

Smads, TAK1, and their common target ATF-2 play a critical role in cardiomyocyte differentiation.

We previously demonstrated that bone morphogenetic proteins (BMPs) induce cardiomyocyte differentiation through the mitogen-activated protein kinase kinase kinase TAK1. Transcription factors Smads mediate transforming growth factor-beta signaling and the ATF/CREB family transcription factor ATF-2 has recently been shown to act as a common target of the Smad and the TAK1 pathways. We here examined the role of Smads and ATF-2 in cardiomyocyte differentiation of P19CL6, a clonal derivative of murine P19 cells. Although P19CL6 efficiently differentiates into cardiomyocytes when treated with dimethyl sulfoxide, P19CL6noggin, a P19CL6 cell line constitutively overexpressing the BMP antagonist noggin, did not differentiate into cardiomyocytes. Cooverexpression of Smad1, a ligand-specific Smad, and Smad4, a common Smad, restored the ability of P19CL6noggin to differentiate into cardiomyocytes, whereas stable overexpression of Smad6, an inhibitory Smad, completely blocked differentiation of P19CL6, suggesting that the Smad pathway is necessary for cardiomyocyte differentiation. ATF-2 stimulated the betaMHC promoter activity by the synergistic manner with Smad1/4 and TAK1 and promoted terminal cardiomyocyte differentiation of P19CL6noggin, whereas overexpression of the dominant negative form of ATF-2 reduced the promoter activities of several cardiac-specific genes and inhibited differentiation of P19CL6. These results suggest that Smads, TAK1, and their common target ATF-2 cooperatively play a critical role in cardiomyocyte differentiation.

Activating Transcription Factor 2↗
PubMed2001

Evidence for the autocrine induction of capacitation of mammalian spermatozoa.

Mammalian spermatozoa require a maturational event after ejaculation that allows them to acquire the capacity for fertilization. This process, known as capacitation, occurs spontaneously in simple defined medium implicating a potential role of autocrine induction. This study shows that the ether phospholipid 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphocholine (PAF) meets the criteria for an autocrine mediator of capacitation. Sperm released PAF after their dilution into capacitation medium and expressed a receptor for PAF on their membranes. PAF stimulated changes in the motility of sperm and enhanced fertilization in vitro. These actions were inhibited by a PAF receptor antagonist (UR-12519) and by extracellular recombinant PAF:acetylhydrolase (an enzyme that degrades PAF to a biologically inert form). Seminal plasma contained an acid-labile PAF:acetylhydrolase, whereas capacitation was inhibited by an acid-labile factor within seminal plasma, implicating this factor as a potential decapacitation factor within seminal plasma. Sperm from a PAF receptor knock-out mouse strain failed to express the receptor and displayed a significantly (p < 0.01) reduced rate of capacitation, as assessed by the spontaneous onset of the acrosome reaction in vitro. When used for in vitro fertilization, sperm from PAF receptor knock-out mice gave a significantly lower rate of fertilization (21.5%) than did wild-type sperm (66.7%). The study shows for the first time the operation of an autocrine loop that induces capacitation in sperm in vitro and shows that this loop acts in concert with other mediators of capacitation to promote efficient fertilization.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2001

Structural analyses of DNA recognition by the AML1/Runx-1 Runt domain and its allosteric control by CBFbeta.

The core binding factor (CBF) heterodimeric transcription factors comprised of AML/CBFA/PEBP2alpha/Runx and CBFbeta/PEBP2beta subunits are essential for differentiation of hematopoietic and bone cells, and their mutation is intimately related to the development of acute leukemias and cleidocranial dysplasia. Here, we present the crystal structures of the AML1/Runx-1/CBFalpha(Runt domain)-CBFbeta(core domain)-C/EBPbeta(bZip)-DNA, AML1/Runx-1/CBFalpha(Runt domain)-C/EBPbeta(bZip)-DNA, and AML1/Runx-1/CBFalpha(Runt domain)-DNA complexes. The hydrogen bonding network formed among CBFalpha(Runt domain) and CBFbeta, and CBFalpha(Runt domain) and DNA revealed the allosteric regulation mechanism of CBFalpha(Runt domain)-DNA binding by CBFbeta. The point mutations of CBFalpha related to the aforementioned diseases were also mapped and their effect on DNA binding is discussed.

Allosteric Regulation↗
PubMed2001

Isolation and characterization of the rat prolactin-releasing peptide gene: multiple TATA boxes in the promoter region.

The prolactin-releasing peptide (PrRP) gene is a novel bioactive peptide expressed in very restricted regions in the brain. To explore the molecular mechanism of PrRP gene expression, we cloned and characterized the gene and its promoter region. The gene spans approximately 2.4 kb and contains three exons and two introns. 3'RACE analysis showed that a polyadenylation signal 103 bp downstream from the stop codon was functional. Primer extension analysis indicated three transcriptional start sites (TSSs) 92, 199, and 325 bp upstream from the translational start site. Interestingly, in addition to the putative binding sites for SP1-1, AP-2, and Oct-2A, three characteristic TATA boxes were identified close to these TSSs. Transient transfection study using a series of deletion mutants revealed that the middle TATA box is important for the promoter activity. Furthermore, the cloned 1.6 kb promoter region was active only in neuron- and pituitary-derived cell lines, and the promoter region -1600 approximately -800 bp worked as a negative regulatory element. We demonstrated for the first time, the genomic organization and promoter function of the PrRP gene, and this knowledge will facilitate elucidation of transcriptional control of the PrRP gene.

3' Untranslated Regions↗
PubMed2001

Introduction of antisense CD44S CDNA down-regulates expression of overall CD44 isoforms and inhibits tumor growth and metastasis in highly metastatic colon carcinoma cells.

We created antisense CD44 transfectants using LS174T, a colon adenocarcinoma cell line and assessed the effects of overall CD44 down-regulation on colorectal tumor growth and metastasis. The expression of antisense CD44s (the standard form of CD44) cDNA markedly inhibited the overall expression of CD44 variants. In vitro studies showed a significantly reduced ability of the stable antisense transfectants (LS174TAS1 and LS174TAS2) to bind hyaluronate and osteopontin, ligands for CD44. These cells developed tumors more slowly than controls (parental LS174T and mock transfectants) when the cells were subcutaneously injected into SCID mice. However, in vitro proliferation assays demonstrated no significant difference between the antisense transfectants and the controls on a hyaluronate-coated surface, suggesting the participation of ligands other than hyaluronate in tumor growth in vivo. Intrasplenic injection of parental LS174T cells produced colonies in the liver in 10 of 11 mice, whereas mice injected with the antisense transfectants were completely free of metastasis. In peritoneal dissemination, the weight of nodules and amount of ascites were significantly reduced in LS174TAS1 and AS2 compared with the controls. In vitro adhesion assays between the transfectants or controls and human peritoneal mesothelial cells revealed that the binding of LS174T cells to mesothelial cells was partly mediated by CD44-hyaluronate interaction. These data suggest that CD44-hyaluronate interaction plays a crucial role in peritoneal dissemination in colorectal carcinoma. The results of our study demonstrate the possible application of antisense CD44s to the treatment of colorectal carcinoma.

Adenocarcinoma↗
PubMed2001

Evaluation of bone metabolic markers in breast cancer with bone metastasis.

PURPOSE: In the present study, four bone metabolic markers were examined to clarify them meaning and clinical value in the detection of bone metastasis (BM) from breast cancer. METHODS: we examined serum carboxyterminal telopeptide of type I collagen (ICTP), tartrate resistant acid phosphatase (TRACP), total alkaline phosphatase (ALP) and urinary type I collagen cross-linked N-telopeptides (NTx) as potential markers. These bone markers were evaluated simultaneously in 156 breast cancer patients; 114 patients without metastasis (group A), 23 patients with BM (group B) and 19 patients with metastasis at sites other than bone (group C). RESULTS: The mean values of ICTP and TRACP in group B were significantly greater than those in group A. Group B consisted of the patients with varying degrees of BM and variation in their treatments. The patients in group B were divided into BM (+) and BM (++) according to hot spots in bone scan. ICTP and TRACP were elevated in BM (++) patients compared to BM (+) patients (p<0.05). The values of ICTP and TRACP of the twelve patients without treatment in group B were significantly higher than those in group A. In the treated patients of group B, the mean values of ICTP and TRACP were lower in responders and cases of stable disease than those with progression. NTx and ALP were inferior to ICTP and TRACP for clinical evaluation of BM. CONCLUSIONS: We confirmed that ICTP and TRACP might be useful markers for screening and monitoring BM in breast cancer.

Acid Phosphatase↗
PubMed2001

Allelic loss of the NF1 gene in anal malignant melanoma in a patient with neurofibromatosis type 1.

A 64-year-old man with neurofibromatosis type 1 (NF1) developed a primary malignant melanoma of the anus. Genetic analysis of the resected tumor confirmed loss of heterozygosity (LOH) of the NF1 gene. Anorectal malignant melanoma in NF1 is extremely rare, and genetic studies of the NF1 gene in such patients have not been reported. The allelic loss detected in the present patient supports the previously raised idea that NF1 can function as a tumor suppressor gene in the development of malignant melanoma in patients with NF1.

Anus Neoplasms↗
PubMed2001

Horse-related injuries in a thoroughbred stabling area in Japan.

To investigate the demographic details and patterns of injuries related to horse handling, we reviewed 637 horse-related injuries in 581 stable- or stud-workers in a representative area of thoroughbred stabling in Japan. We found that (1) injuries occurred most frequently in a group of a relatively young workers, with a seasonal variation; (2) the principal mechanism of injury was kicks, which accounted for 39.2% of all injuries, including 11 serious and one lethal visceral injuries; (3) the upper half of the body was more frequently involved than the lower half; and (4) the peripheral bones (hand and foot) and the ribs accounted for more than half of 148 fractures. These findings are distinct from those in horse-riding injuries reported in the literature and emphasize the importance in developing preventive strategies specifically for workers in horse stables.

Accidents, Occupational↗
PubMed2001

Effects of preconditioning on ischemia/reperfusion injury of hepatocytes determined by immediate early gene transcription.

Ischemia reperfusion (I-R) of the liver induces various events leading to cell death (apoptosis) and subsequent cells proliferation. Recent experimental studies have described the protective effect of ischemic preconditioning (IPC) on I-R injury of the liver. However, the mechanisms involved in this protection remain unknown. The protein products of immediate early genes (IEGs) behave as crucial transcriptional regulators not only in apoptosis but also in cell proliferation. Here, we evaluated the effects of IPC on IEG transcription after I-R injury, using a rat liver I-R injury model. Injury to hepatocytes was evaluated by measuring serum levels of aspartate transaminase (AST), alanine transaminase (ALT), and lactate dehydrogenase (LDH) and that to endothelial cells by plasma concentration of hyaluronic acid (HA). The extent of necrosis was evaluated by H&E staining, while cell proliferation and apoptosis were evaluated by proliferating cell nuclear antigen (PCNA) and terminal deoxy(d)-UTP nick end labelling (TUNEL) staining, respectively. Alterations in the transcription of IEGs (c-fos and c-jun) were examined by Northern blotting. Rats subjected to 40-min liver ischemia, preceded by 10-min preconditioning, showed significantly lower AST, ALT, LDH, and HA levels at 6 h after I-R than untreated animals (P < 0.05; n at least 5 rats per group). The percentage of necrotic areas at 24 h after I-R was significantly lower in IPC-treated animals than in the controls. The numbers of apoptotic cells at 24 h after I-R and the numbers of PCNA-positive cells at 24 and 48 h after I-R were significantly lower in IPC-treated rats than in controls. Transcription levels of IEGs were low in IPC-treated rats, particularly c-jun at 1 and 1.5 h after I-R (P < 0.05). Our results indicate that IPC provides a significant protective effect on for liver cells against I-R injury and that its effect is evidenced by a significant decrease in the transcription levels of IEGs following the insult.

Animals↗
PubMed2001

Induction of immediate early genes after partial hepatectomy in cholestatic liver.

The protein products of immediate early genes (IEGs) behave as transcriptional regulators and play an important role in the regulation of gene expression associated with liver cell proliferation and apoptosis. The aim of this study was to examine whether the transcription of IEGs was induced by obstructive jaundice during liver regeneration after 70% partial hepatectomy, and to examine their association with animal survival, cell proliferation, and apoptosis. Obstructive jaundice (OJ) was induced in rats by common bile duct ligation (CBDL), and 70% partial hepatectomy was performed 5 days after CBDL (OJ group). Changes in the induction of the IEGs, c-fos and c-jun, were compared between control and OJ groups in relation to survival before and after partial hepatectomy. Cell proliferation and apoptosis were evaluated by proliferating cell nuclear antigen (PCNA) immunohistological staining and by an in situ TdT-mediated d-UTP-digoxigerin nick-end labeling (TUNEL) method. The 2-week survival in the OJ group (2/7) was significantly less that of the sham operation (control) group (7/7). Enhanced induction of IEGs was evident in the OJ group after partial hepatectomy compared with findings in the control group. The PCNA-labeling index (LI) in the OJ group was increased after partial hepatectomy, but only minimally, compared with that in control animals. Apoptotic cells appeared in bile ducts and surrounding hepatocytes after partial hepatectomy in the OJ group, although apoptotic cells were rare in the control group. IEG transcription does occur after partial hepatectomy in jaundiced liver but it is enhanced and sustained, and leads to apoptosis rather than leading to the efficient proliferation of hepatocytes.

Animals↗
PubMed2001

Environmental occurrence of nitrotriphenylene observed in airborne particulate matter.

1- and 2-Nitrotriphenylenes were found in the airborne particulate matter extracts collected in central Tokyo between the winter of 1998 and the winter of 1999. In particular, we have identified and quantified nitrotriphenylenes in the airborne particulate matter extracts collected over four consecutive 6-h periods on 2 December 1999. The concentrations of 1- and 2-nitrotriphenylene ranged from 0.04 to 0.44 and from 0.02 to 0.47 ng/m3, respectively, and the concentrations in the airborne particulate matter extracts collected during the 18:00-24:00 h time period were the highest of the four collection periods. 1-Nitropyrene and 2-nitrofluoranthene were also identified and quantified in the four 6-h samples. Although the concentrations of 1- and 2-nitrotriphenylenes were not higher than that of 2-nitrofluoranthene except during the 18:00-24:00 h time period, the concentrations were much higher than that of 1-nitropyrene during the four collection periods. The higher concentrations of 1- and 2-nitrotriphenylenes during the 18:00-24:00 h time period are presumably responsible for the high reactivity of parent triphenylene with NO2/NO3/N2O5, and high stability of 1- and 2-nitrotriphenylenes toward O3 + O2. In addition, the observed isomer distribution of nitrotriphenylenes suggested that direct emission of nitrotriphenylenes is also a source as well as their atmospheric formation.

Air Pollutants↗
PubMed2001

Early anchoring collagen fibers at the bone-tendon interface are conducted by woven bone formation: light microscope and scanning electron microscope observation using a canine model.

To clarify the early process of recovery at the bone-tendon interface, we used light microscopy and SEM to examine the process of anchoring of collagen fibers to bone in a canine model. At two weeks, tendon, scar tissue, woven bone and lamellar bone were present at the insertion site. SEM revealed anchoring of collagen fibril bundles of the scar to the woven bone. By 4 weeks, the number of anchoring fibers had increased and a parallel arrangement of fibers was observed. SEM demonstrated deep penetration of fibers into the woven bone layer. In addition, the fibers were observed to project into and intermingle with the scar tissue. By 6 weeks, the anchoring fibers had developed fully and were distributed densely over the interface. SEM also revealed that the collagen fibril bundles in the scar tissue had connected with the collagen fibrils of the woven bone by way of the anchoring bundles. The woven bone was identifiable throughout the early stages of recovery as the interface between soft tissue and hard tissue. Throughout all experimental periods, no staining was observed at the interface of the tendon and bone by Saffranin-O. The formation of woven bone was important during early recovery of the tendon-bone interface prior to the completion of fibrocartilage-mediated insertion.

Animals↗
PubMed2001

Reconstruction of chaotic dynamics by on-line EM algorithm.

In this paper, we discuss the reconstruction of chaotic dynamics by using a normalized Gaussian network (NGnet), which is a network of local linear regression units. The NGnet is trained by an on-line EM algorithm in order to learn the vector field of the chaotic dynamics. We investigate the robustness of our approach to two kinds of noise processes: system noise and observation noise. System noise disturbs the system dynamics itself. Observation noise is added when the state variables are observed. It is shown that the trained NGnet is able to reproduce a chaotic attractor, which approximates the complexity and instability of the original chaotic attractor well, even under various noise conditions. The trained NGnet also shows good prediction performance. When only part of the dynamical variables are observed, the delay embedding method is used. The NGnet is then trained to learn the vector field in the delay coordinate space. Experiments show that the chaotic dynamics embedded in the delay coordinate space is able to be learned under the two types of noise.

Algorithms↗
PubMed2001

Synthesis and preliminary evaluation of a carbon-11-labeled adenosine transporter blocker [(11)C]KF21562 .

We prepared an (11)C-labeled adenosine transporter blocker, [1-methyl-(11)C]-3-[1-(6,7-dimethoxyquinazolin-4-yl)piperidin-4-yl]-1,6-dimethyl-2,4(1H, 3H)-quinazolinedione ([(11)C]KF21652) and examined its potential as a positron emission tomography (PET) ligand for mapping adenosine transporters in the brain and peripheral organs. The log P(7.4) value of KF21652 was 3.14, and the K(i) value was 13 nM for adenosine transporters using [(3)H]nitrobenzylthioinosine as a radioligand. In mice, the highest initial uptake was found in the liver, followed by the kidney and small intestine. The brain uptake was very low. The radioactivity level slightly increased with time in the liver and small intestine, but decreased in the other organs. Coinjection of carrier KF21652 slightly decreased the uptake of [(11)C]KF21562 only in the liver, but not in any other organs. Ex vivo autoradiography of the rat brain showed that [(11)C]KF21652 was scarcely incorporated into the brain. On the other hand, in vitro autoradiography showed the binding of [(11)C]KF21562 to adenosine transporters with high nonspecific binding. These results show that the compound is not a suitable PET ligand for mapping adenosine transporters.

Adenosine↗