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T Sakai

Publications and source records attributed to T Sakai.

At least 541 records · Page 30Linked to original sources
PubMed1997

Retinoblastoma binding factor 1 site in the core promoter region of the human RB gene is activated by hGABP/E4TF1.

We previously reported two oncogenic point mutations present in the RB (retinoblastoma) gene promoter region, found at consensus Sp1 and ATF sites, respectively, and in two separate hereditary RB families. However, Sp1 protein was shown not to bind to the Sp1 site; this indicated that the Sp1 consensus site mutation was blocking the action of an alternative transcription factor, which we called RBF-1 (retinoblastoma binding factor 1). Subsequent purification of RBF-1 revealed it to be hGABP/E4TF1, a transactivator from the adenovirus early-region 4 promoter. In this study, we directly examined the effects of hGABP/E4TF1 on transactivation of the RB gene promoter through the RBF-1 site. As expected, hGABP/E4TF1 enhanced the core RB promoter activity, whereas it did not stimulate a mutant RBF-1 site. We therefore conclude that the most essential transcription factor in the human RB gene is likely to be hGABP/E4TF1.

Animals↗
PubMed1997

Molecular cloning and characterization of the human p27Kip1 gene promoter.

p27Kip1 is an inhibitor of multiple cyclin-dependent kinases (cdk), and can arrest the cell-cycle progression by inhibiting the phosphorylation of the retinoblastoma gene family products. Tumor formation in p27Kip1 knockout mice clearly shows that p27Kip1 plays an important role in inhibiting tumor formation and progression. To investigate the mechanism of transcriptional p27Kip1 gene expression, we isolated the genomic DNA fragment of the 5' flanking region of the human p27Kip1 gene and characterized its promoter region. The human p27Kip1 promoter is TATA-less, and the sequence is highly homologous to the murine p27Kip1 promoter sequence. In the promoter assay, deletion from -774 to -435 relative to the initiating codon resulted in a 15-20-fold reduction of the p27Kip1 promoter activity, suggesting that the elements for basal promoter activity exist in this highly conserved 340 bp region, where putative CTF and ATF sites are conserved.

Animals↗
PubMed1997

Schizophrenia and the ciliary neurotrophic factor (CNTF) gene: no evidence for association.

The ciliary neurotrophic factor (CNTF) gene is considered a candidate gene for schizophrenia, in view of the neurodevelopmental hypothesis of the disorder. Recently, controversial results regarding an association between psychiatric disorders; mainly schizophrenia, and a null mutation of the CNTF gene were reported. We investigated this mutation in 138 Japanese patients with schizophrenia and 140 healthy control subjects. No significant difference was observed in allele frequencies or genotype distribution between the patients and control subjects. Our results did not provide evidence for the involvement of the null mutation of the CNTF gene in the development of schizophrenia.

Adult↗
PubMed1997

Regulatory effects of aggregated LDL on apoptosis during foam cell formation of human peripheral blood monocytes.

In order to investigate the mechanisms how modified lipoproteins enhance foam cell formation, we cultured peripheral blood monocytes with various stimulants and examined the effects of aggregated low-density lipoprotein (agLDL) on cell viability and lipid metabolism. AgLDL could completely inhibit phorbol ester-induced apoptosis, which was accompanied by intracellular cholesterol accumulation. Suppression of apoptosis-promoting proteases, ICE and CPP32, was observed in agLDL-treated cells. This indicates that agLDL accelerates foam cell formation through inhibition of apoptosis and enhancement of lipid accumulation in activated monocytes. By contrast, apoptosis was enhanced when monocytes were cultured with agLDL and M-CSF. Intracellular cholesterol accumulation was not significant in M-CSF treated cells. This suggests that M-CSF may act anti-atherogenic through apoptotic elimination of lipid-baring macrophages and enhanced lipid turnover. Our observation supports the novel hypothesis that regulation of apoptosis may play an important role in the development of atherosclerosis.

Apoptosis↗
PubMed1997

Genes for interleukin-2 receptor beta chain, interleukin-1 beta, and schizophrenia: no evidence for the association or linkage.

We studied a CA repeat polymorphism of the interleukin-2 receptor beta chain (IL-2RB) gene and a C/-514/T variation of the interleukin-1 beta (IL-1B) gene in Japanese schizophrenia patients. Both a case-control association study (54 patients and 54 controls) and a linkage study using six multiplex families (the number of the affected > or =4 in each family) were employed. No evidence for the association or the linkage was obtained either for the IL-2RB or IL-1B gene.

Alleles↗
PubMed1997

The glycoproteins that occur in the colloids of senescent porcine pituitary glands are clusterin and glycosylated albumin fragments.

Periodic acid-Schiff-positive colloids occur in the pituitary glands of many vertebrates. These colloids are surrounded by folliculo-stellate (FS) cells and increase dramatically in number and size with age. The characterization of these colloidal substances is necessary for the establishment of FS cell function. In a previous study we showed that these colloids in the senescent pituitary contain a number of glycoproteins; however, the characterization of these glycoproteins has not yet been carried out. To characterize the pituitary colloid, we purified the colloids by centrifugation and Percoll gradient. The isolated colloids were unable to be solubilized in a regular buffer since they were very dense. However, solubilization was accomplished in sodium dodecyl sulfate (SDS) lysis buffer following treatment with exoglycosidase. Analysis using SDS-polyacrylamide gel electrophoresis showed that the porcine pituitary colloids contain four proteins, CP26, CP40, CP48 and CP60, whose estimated molecular weights were 26 kD, 36-43 kD, 48 kD, and 60 kD, respectively. Staining with concanavalin A (ConA) showed that both CP26 and CP40 were glycoproteins. Moreover, N-terminal amino acid sequencing and Western blot analysis revealed CP26, CP48 and CP60 to be porcine albumin while CP40, the major protein in the colloids, proved to be clusterin. Therefore we report here that the glycoproteins that occur in senescent porcine pituitary colloids are of two types, namely, albumin fragments and clusterin.

Aging↗
PubMed1997

T/G polymorphism at intron 9 of presenilin 1 gene is associated with, but not responsible for sporadic late-onset Alzheimer's disease in Japanese population.

To investigate whether presenilin 1 (PS1) gene, a major causative gene of familial early-onset Alzheimer's disease (AD), also contributes to the etiology of sporadic AD, we evaluated associations between Japanese AD and polymorphisms located at 14q24.3. While the D14S43 and FOS loci showed no association with either early- or late-onset AD, late-onset AD carrying no APOE-epsilon4 allele was associated with the G allele of the T/G polymorphism located at intron 9 of the PS1 gene (P = 0.016). Considering another study showing a positive association between AD and the T allele, this polymorphism is associated with, but not responsible for sporadic late-onset Alzheimer's disease.

Age of Onset↗
PubMed1997

Molecular cloning and nucleotide sequence of an endo-1,5-alpha-L-arabinase gene from Bacillus subtilis.

The nucleotide sequence of the gene encoding an endo-1,5-alpha-L-arabinase (protopectinase C) of Bacillus subtilis was determined by sequencing fragments amplified by the cassette-ligation-mediated PCR (CLM-PCR). The gene covering the start and stop codon was amplified by PCR with two specific primers, which were designed from the sequence data determined by CLM-PCR. An approximately 1.5-kb amplification product was cloned into the vector pUC119, forming a plasmid termed pPPC. An ORF that encodes the arabinase composed of 324 amino acids including a 33-amino-acid signal peptide was assigned. Comparison of the deduced amino acid sequence of the enzyme with that of an Aspergillus niger endoarabinase showed 37% identity in a 207-amino-acid overlap. The optimal nucleotide sequence for catabolite repression of B. subtilis was found upstream of the structural gene. In a culture of Escherichia coli DH5alpha cells harboring pPPC, no arabinase activity was detected, either intracellularly or extracellularly, suggesting that the B. subtilis promotor is not functional in this transformant. In B. subtilis IFO 3134 strain, production of protopectinase C was repressed by readily metabolizable carbohydrates. In contrast, productivity (total enzyme activity/bacterial growth) of the enzyme was increased about fourfold in the presence of 0.75 M potassium phosphate in the culture medium. The phosphate anion seemed to be involved in the stimulation of protopectinase C production in this stain.

Amino Acid Sequence↗
PubMed1997

Association between early-onset alcoholism and the dopamine D2 receptor gene.

We examined the allelic association between the dopamine D2 receptor (DRD2) gene and alcoholism in 100 biologically unrelated Japanese alcoholics and 93 unrelated controls. Genomic DNA was prepared from peripheral white blood cells using the phenol-chloroform method. A 310-bp region surrounding the TaqA site at the DRD2 locus was amplified by polymerase chain reaction (PCR), and the PCR product was incubated with TaqI. The A1 allele remained intact while the A2 allele was cut. The frequency of the A1/A1 genotype and the frequency of the A1 allele were higher in early-onset alcoholics than in controls, P < 0.05 and P < 0.01, respectively. Moreover, the frequency of the A1/A1 genotype and the frequency of the A1 allele were higher in early-onset alcoholics with family histories of alcohol dependence than in controls, P < 0.01 and P < 0.01, respectively. The results indicate that the DRD2 gene is associated with susceptibility to early-onset alcoholism, and that each additional A1 allele shifts onset of alcoholism to an earlier age.

Adult↗
PubMed1997

Fibroblasts spread on immobilized fibrin monomer by mobilizing a beta1-class integrin, together with a vitronectin receptor alphavbeta3 on their surface.

Human and murine fibroblasts were found to spread far more avidly on fibrin monomer monolayers than on immobilized fibrinogen, indicating that removal of fibrinopeptides by thrombin is a prerequisite for the fibrin-mediated augmentation of cell spreading. In fact, cell spreading was not efficiently augmented on monolayers of a thrombin-treated dysfibrinogen lacking the release of fibrinopeptide A due to an Aalpha Arg-16 --> Cys substitution. Since a synthetic Arg-Gly-Asp (RGD)-containing peptide inhibited the fibrin-mediated cell spreading, subsequent dissociation of the carboxyl-terminal globular domain of the Aalpha-chains appears to render the RGD segments accessible to the cell-surface integrins. In support of this, fibrin-augmented cell spreading was inhibited by an antibody recognizing a 12-kDa peptide segment with gamma Met-89 at its amino terminus, which is located in close association with the RGD segment at Aalpha 95-97 in the helical coiled-coil interdomainal connector. The fibrin-mediated augmentation of cell spreading was inhibited not only by an antibody against human vitronectin receptor (LM 609) but also by an antibody against the beta1 subunit of integrin (mAb13), suggesting that the beta1-class integrin together with a vitronectin receptor, alphavbeta3, is mobilized onto the surface of fibroblasts upon contact with the fibrin monomer monolayer.

Animals↗
PubMed1997

Rapid internalization of exogenous ganglioside GM3 and its metabolism to ceramide in human myelogenous leukemia HL-60 cells compared with control ganglioside GM1.

Incorporation and metabolism of exogenous GM3 in human myelogenous leukemia HL-60 cells were analyzed using 3H-labeled GM3 ([3H]GM3). [3H]GM3 was rapidly internalized into the cells (trypsin-resistant fraction) 8 times more than the control, 3H-labeled GM1 ([3H]GM1). In addition, not only incorporation but also metabolism of [3H]GM3 was more rapid than [3H]GM1 in HL-60 cells. Moreover, one of the metabolites was found to co-migrate with ceramide in thin-layer chromatography analysis and ceramide formation from exogenous GM3 is more rapid than that from exogenous GM1. These results suggested that there would be some preferential mechanism to produce ceramide from differentiation-inducible GM3 in HL-60 cells rather than from non-inducing GM1.

Cell Membrane↗
PubMed1997

Immunological effects of CaEDTA injection: observations in two lead workers.

To evaluate the effects of calcium disodium ethylenediamine tetraacetate (CaEDTA) injection on human immune system in relation to exposure to lead, we administered CaEDTA by intravenous injection for 1 hr three times (three consecutive days) a week to two male lead workers. They had been engaged in recycling lead for 31 and 22 years, aged 61 and 53 years (workers 1 and 2), respectively. Before the treatment of CaEDTA, their blood lead concentrations (PbB) were 81 and 68 micrograms/dl, respectively. The administration of CaEDTA had been carried out to worker 1 for 10 weeks and to worker 2 for 6 weeks. A significant decrease in PbB between before and after three-times CaEDTA injection was found in both workers. Significant increases in IgG, IgA, IgM, CD8+, and CD57+ cells were found in worker 1. A significant increase in IgD was found in worker 2. During the study period, IgG in worker 1 and CD4+ cells in worker 2 were gradually increasing. There was a significant negative correlation between IgG and PbB in worker 1. It is suggested that the immunological function such as antibody formation in lead workers might be improved by CaEDTA injection.

Antibody Formation↗
PubMed1997

alpha 1-Antichymotrypsin as a risk modifier for late-onset Alzheimer's disease in Japanese apolipoprotein E epsilon 4 allele carriers.

In the Japanese population, sporadic late-onset Alzheimer's disease (LOAD) cases had significantly higher frequencies of the A allele of alpha 1-antichymotrypsin (ACT) gene as well as the epsilon 4 allele of apolipoprotein E (APOE) gene than controls. The odds ratio for LOAD in APOE4 carriers with the ACT-A allele was more than six times that in APOE4 carriers without the ACT-A allele (21.1 vs 3.2). These results indicate that the ACT-A allele is a risk modifier for LOAD in APOE4 carriers.

Age of Onset↗
PubMed1997

Decreased cerebrospinal fluid levels of substance P in patients with Rett syndrome.

To clarify the mechanism of brain and spinal cord impairment in Rett syndrome (RS), we measured the cerebrospinal fluid (CSF) levels of substance P in 20 patients with RS including 16 childhood patients and 4 adult patients. Findings were compared with those obtained in age-matched controls and diseased controls. The CSF level of substance P was significantly lower in patients with RS compared with controls. The alteration in the CSF level of substance P may be related to the neurological impairment, especially autonomic dysfunction, and neuropathological involvement of dorsal root ganglia and peripheral nerve observed in RS.

Adult↗
PubMed1997

Recovery of mucin content in surface layer of rat gastric mucosa after HCl-aspirin-induced mucosal damage.

Quantitative changes in mucin (mucus glycoprotein) in different layers of rat gastric mucosa after mucosal damage induced by acidified acetylsalicylic acid (HCl-aspirin; 0.15N HCl, 20-200 mg acetylsalicylic acid/kg body weight) were studied. More than 50 mg/kg HCl-aspirin led to a significant increase in macroscopic gastric injury (expressed as ulcer index) at 3 h, compared with control (no aspirin) and there was a significant recovery at 7 h. Three h after dosing with 50 mg/kg acidified aspirin, there was superficial mucosal damage and decreased mucin content in the surface mucosal layer. Mucin production recovered 7 h after the administration of 50 mg/kg acidified aspirin. Doses of acidified aspirin higher than 100 mg/kg decreased mucin content in the surface and deep corpus mucosal layers and no recovery was seen 7 h after the administration. Physiological damage after the administration of 50 mg/kg HCl-aspirin was limited mainly to surface epithelial mucus cells. An experimental model in which superficial erosion was induced in rat gastric mucosa was established with low-dose HCl-aspirin.

Animals↗
PubMed1997

Influence of extravariceal collateral channel pattern on recurrence of esophageal varices after sclerotherapy.

We investigated the influence of extravariceal collateral channel pattern on the recurrence of esophageal varices after sclerotherapy. One hundred and fifteen patients with cirrhosis and esophageal varices were studied. They were divided into four groups according to extravariceal collateral pattern on portal venography. Group 1 patients had neither paraesophageal veins nor gastrorenal veins (n = 49); group 2 patients had paraesophageal veins only (n = 30); group 3 patients had gastrorenal veins only (n = 25); and group 4 patients had paraesophageal veins plus gastrorenal veins (n = 11). Sclerotherapy was repeated to eradicate esophageal varices and follow-up endoscopic examination were performed. The overall recurrence-free rate at 36 months was 68%. The log-rank test showed the recurrence-free rate to be significantly higher in group 3 (76%) and group 4 patients (89%) than in group 1 patients (51%; P < 0.05 and P < 0.05, respectively). Although the recurrence-free rate was higher in group 4 than in group 2 patients (59%), this did not reach the level of significance (P = 0.10). No significant differences were found between other pairs of groups. These results suggest that gastrorenal veins play an important role in the protection against recurrent esophageal varices after sclerotherapy, while the protective role of paraesophageal veins appears to be small.

Aged↗