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H Aoki

Publications and source records attributed to H Aoki.

At least 127 records · Page 7Linked to original sources
PubMed1998

p53-independent WAF1 induction by ACNU in human glioblastoma cells.

The induction of WAF1 gene expression after the treatment with the anticancer agent 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU; nimustine hydrochloride) was studied in two human glioblastoma cell lines: U-87MG, which bears the wild-type p53 gene, and T98G, which bears the mutant p53 gene. A marked accumulation of WAF1 was observed 3 h after ACNU treatment in both cell lines. The induction of WAF1 mRNA by ACNU was detected by northern blot analysis in these cells. Binding activity of p53 to a p53 consensus sequence increased after treatment in U-87MG cells but not in T98G cells. The existence of a p53-independent WAF1 induction pathway was supported by the apparent accumulation of WAF1 after ACNU treatment in the p53-null human osteosarcoma cell line Saos-2. These findings suggest that there are two possible pathways for WAF1 induction: the p53-dependent pathway through the p53-responsive element and the p53-independent pathway through other elements.

Antineoplastic Agents↗
PubMed1998

Frequent alterations of cell-cycle regulators in astrocytic tumors as detected by molecular genetic and immunohistochemical analyses.

Alterations of CDKN2A, RB, and cyclin D1 genes and expression of their products in astrocytic tumors were studied using a combination of molecular genetic and immunohistochemical assays. In addition, the association of gene status with clinical outcome was evaluated. Alterations of CDKN2A and RB gene in 30 lesions were analyzed by single-strand conformation polymorphism of polymerase chain reaction (PCR-SSCP), direct sequencing, and Western blotting. Methylation of the CDKN2A promoter was detected by methylation-specific PCR. Immunohistochemistry was applied to determine the expression of gene products in tumors from 94 patients for whom clinical outcome was also evaluated. Analyses of the CDKN2A gene revealed 12 homozygous or hemizygous deletions, one mutation in exon 1, and three methylations in the promoter. Expression of p 16 protein was not detected in 18 of 30 cases. RB mutations leading to loss of expression of the pRb were found in four (13%) cases, and six were immunohistochemically negative for this protein. Overexpression of cyclin D1 was obtained in 51 (54%) of 94 cases. Patients with pRb-negative tumors had a significantly greater risk of earlier death than those with p16 and cyclin D1 alterations, Both p16 and pRb immunohistochemistry provides useful complementary information and may provide valuable predictive information in screening. The biological consequences of deregulating individual components along cell control pathways are unequal, perhaps reflecting their hierarchical roles in the G1 checkpoint.

Adolescent↗
PubMed1998

Genetic variations in recurrent astrocytic tumors detected by restriction landmark genomic scanning.

The genetic mechanisms associated with recurrence of advanced astrocytic tumors are poorly understood. We therefore analyzed 24 biopsy specimens from 12 patients with a recurrent astrocytic tumor by a two-dimensional gel electrophoresis method, termed restriction landmark genomic scanning (RLGS). Four spot changes were commonly present in the primary astrocytomas, indicating that the corresponding gene alterations were early events in the development of this tumor type. Altered spots were more frequent and of different distribution in recurrent tumors than in the primary astrocytomas. In particular, specifically increased intensity for spots on chromosomes 9-12 and 18 were observed in the secondary tumors, suggesting a relation with recurrence. The same spot changes observed in primary tumors were also found in the respective secondary lesions but with strikingly different densities in some cases, suggesting increased genetic instability. The altered segments provide important candidate regions for the search for genes involved in events leading to progression and more malignant recurrent tumors.

Astrocytoma↗
PubMed1998

Subdural osteoma.

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Dura Mater↗
PubMed1998

Effects of protein kinase inhibitors on heat-induced hsp72 gene expression in a human glioblastoma cell line.

We examined the effects of several kinds of protein kinase inhibitors against calcium/phospholipid-dependent protein kinase (PKC) and cAMP-dependent protein kinase (PKA) on heat-induced hsp72 gene expression in a human glioblastoma cell line (T98G) as a source of insight into the type of protein kinase contributing to its gene expression. When the cells were treated with 1-(5-isoquinolinesulphonyl)-2-methylpiperazine [(H7) a potent inhibitor of PKC, PKA, and others], the suppression of heat-induced Hsp72 accumulation was observed. Heat-induced Hsp72 accumulation was also suppressed by staurosporine (a potent inhibitor of PKC and PKA) or calphostin C [(CAL) a potent inhibitor of PKC] at high concentration (10 x IC50) but not at low concentration (1 x IC50). N-(2-(p-Bromocinnamylamino)ethyl]-5-isoquinolinesulphonamide [(H89) a potent inhibitor of PKA] did not affect heat-induced Hsp72 accumulation at either low (1 x IC50) or high concentrations (10 x IC50). Combination treatment with CAL and H89 suppressed the heat-induced Hsp72 accumulation more strongly than did treatment with either inhibitor alone. Furthermore, the heat-induced DNA-binding activation of heat-shock factor (HSF) was suppressed by CAL at high concentration (10 x IC50), and combination treatment with CAL and H89 showed stronger suppression. In the H7 treatment, the clear suppression of HSF activation was observed even at low concentration (1 x IC50). In addition, the cellular content of Hsp72 increased after the treatment of PKC or PKA activator. These results suggest that not only PKC, but also PKA may play an important role in heat-induced hsp72 gene expression.

Blotting, Western↗
PubMed1998

In vivo and in vitro studies of the inhibitory effect of propofol on human platelet aggregation.

BACKGROUND: The inhibitory effects of propofol on platelet aggregation are controversial because the fat emulsion used as the solvent for propofol may affect platelet function. The effects of propofol on platelet intracellular calcium ion concentration and on aggregation were investigated. METHODS: Platelet aggregation was measured in 10 patients who received an intravenous infusion of propofol. Intralipos, the propofol solvent, was infused in 10 healthy volunteers and platelet aggregation were measured. The in vitro effects of propofol and Intralipos on platelets were also investigated. The inhibitory effects of various concentrations of propofol were studied. The effects of propofol on the changes in intracellular calcium level using a fluorescent dye, fura-2, were also observed. Template bleeding time was measured to determine the effect of propofol in clinical use. RESULTS: Platelet aggregation was significantly inhibited by infusion of propofol, although bleeding time was not prolonged. Intralipos did not inhibit platelets either in vivo or in vitro. Propofol significantly inhibited platelet aggregation in vitro and at 5.81 +/- 2.73 microg/ml but not at 2.08 +/- 1.14 microg/ml. The increase of intracellular calcium concentration was inhibited both in influx and discharge of calcium. CONCLUSIONS: Propofol inhibited platelet aggregation both in vivo and in vitro. Inhibition of platelet aggregation appeared to be caused by propofol itself and not by the fat emulsion. This inhibitory effect was also supported by the suppressed influx and discharge of calcium. No change in the bleeding time suggests that this inhibitory effect does not impair hemostasis clinically.

Adult↗
PubMed1998

The oxazolidinone linezolid inhibits initiation of protein synthesis in bacteria.

The oxazolidinones represent a new class of antimicrobial agents which are active against multidrug-resistant staphylococci, streptococci, and enterococci. Previous studies have demonstrated that oxazolidinones inhibit bacterial translation in vitro at a step preceding elongation but after the charging of N-formylmethionine to the initiator tRNA molecule. The event that occurs between these two steps is termed initiation. Initiation of protein synthesis requires the simultaneous presence of N-formylmethionine-tRNA, the 30S ribosomal subunit, mRNA, GTP, and the initiation factors IF1, IF2, and IF3. An initiation complex assay measuring the binding of [3H]N-formylmethionyl-tRNA to ribosomes in response to mRNA binding was used in order to investigate the mechanism of oxazolidinone action. Linezolid inhibited initiation complex formation with either the 30S or the 70S ribosomal subunits from Escherichia coli. In addition, complex formation with Staphylococcus aureus 70S tight-couple ribosomes was inhibited by linezolid. Linezolid did not inhibit the independent binding of either mRNA or N-formylmethionyl-tRNA to E. coli 30S ribosomal subunits, nor did it prevent the formation of the IF2-N-formylmethionyl-tRNA binary complex. The results demonstrate that oxazolidinones inhibit the formation of the initiation complex in bacterial translation systems by preventing formation of the N-formylmethionyl-tRNA-ribosome-mRNA ternary complex.

Acetamides↗
PubMed1998

[Factors contributing to an increase in DLco (steady state) after exercise in healthy men].

We studied factors contributing to an increase of DLco (steady state) from rest to exercise in 10 healthy men. DLco(ss), Dm, and Vc were measured under three different conditions, rest, constant load exercise (50 watts), and hyperventilation (equal to the tidal volume and respiratory rate of exercise). DLco(ss) increased significantly during exercise and hyperventilation compared with at rest. DLco(ss) also increased significantly during exercise, compared with hyperventilation. During constant load exercise (50 watts) increased Dm and Vc, caused by increased ventilation, together with increased of Vc caused by increased of pulmonary blood flow resulted in an increase in DLco(ss).

Adult↗
PubMed1998

[One year follow-up of pulmonary rehabilitation in patients with pulmonary emphysema--physiological outcome].

To evaluate the long-term effects of pulmonary rehabilitation on physiological outcome, 12 patients with pulmonary emphysema were enrolled in an inpatient pulmonary rehabilitation program for 6 weeks. After discharge from the hospital, they were followed up for 1 year. The pulmonary rehabilitation program consisted of breathing retraining, thoracic mobilization, exercise training, and patient education. Although the subjects did not participate in outpatient maintenance group sessions after their discharge, they continued breathing retraining and exercise training at home. Their vital capacity improved significantly, and was sustained over the course of the year; other pulmonary functions, however, did not change significantly. Maximum exercise load increased 31% after the rehabilitation program; although it was 18% higher than baseline at follow-up one year later, that was not a significant change. The follow-up data on exercise traming had generally deteriorated 1 year after the rehabilitation program. The change in maximum exercise load from baseline before and after the inpatient pulmonary rehabilitation program correlated closely with the change in maximum exercise load thereafter to follow-up one year later (R = 0.62). We conclude that it is pessible to estimate long-term change in exercise capacity on the basis of short-term changes achieved during inpatient pulmonary rehabilitation. It may be necessary to develop maintenance programs of some kind to help pulmonary emphysema patients retain the benefits of pulmonary rehabilitation over the longer term.

Aged↗
PubMed1997

The gene encoding the elongation factor P protein is essential for viability and is required for protein synthesis.

Elongation factor P (EFP) is a protein that stimulates the peptidyltransferase activity of fully assembled 70 S prokaryotic ribosomes and enhances the synthesis of certain dipeptides initiated by N-formylmethionine. This reaction appears conserved throughout species and is promoted in eukaryotic cells by a homologous protein, eIF5A. Here we ask whether the Escherichia coli gene encoding EFP is essential for cell viability. A kanamycin resistance (KanR) gene was inserted near the N-terminal end of the efp gene and was cloned into a plasmid, pMAK705, that has a temperature-sensitive origin of replication. After transformation into a recA+ E. coli strain, temperature-sensitive mutants were isolated, and their chromosomal DNA was sequenced. Mutants containing the efp-KanR gene in the chromosome grew at 33 degrees C only in the presence of the wild-type copy of the efp gene in the pMAK705 plasmid and were unable to grow at 44 degrees C. Incorporation of various isotopes in vivo suggests that translation is impaired in the efp mutant at 44 degrees C. At 44 degrees C, mutant cells are severely defective in peptide-bond formation. We conclude that the efp gene is essential for cell viability and is required for protein synthesis.

Chromosomes, Bacterial↗
PubMed1997

Interlamellar waters in dimyristoylphosphatidylethanolamine-water system as studied by calorimetry and X-ray diffraction.

The number of water molecules incorporated into the interlamellar region in a gel phase of dimyristoylphosphatidylethanolamine (DMPE)-water system containing up to about 40 g% water was estimated by techniques of calorimetry and X-ray diffraction. The calorimetric estimation based upon enthalpy changes of deconvoluted ice-melting peaks revealed that bulk water existing outside lipid bilayers begins to appear although the gel phase is not fully hydrated. The gel phase showed a linear depression of its transition temperature proportional to the amount of freezable waters interposed between bilayers. For a fully hydrated gel phase, the numbers of non-freezable and freezable interlamellar waters estimated by calorimetric analysis were about 2.3 and 3.7 molecules per lipid, respectively. The limiting, total number of interlamellar waters, 6 H2O/lipid, agreed with that estimated from both the X-ray diffraction data and the absolute specific volume for a DMPE molecule. Furthermore, the analysis for the lamellar intensity data is also consistent with the result of calorimetric analysis.

Calorimetry, Differential Scanning↗
PubMed1997

Angiotensin II type1a receptor gene expression in the heart: AP-1 and GATA-4 participate in the response to pressure overload.

Hypertrophy of mammalian cardiac muscle is mediated, in part, by angiotensin II through an angiotensin II type1a receptor (AT1aR)-dependent mechanism. To understand how the level of AT1aRs is altered in this pathological state, we studied the expression of an injected AT1aR promoter-luciferase reporter gene in adult rat hearts subjected to an acute pressure overload by aortic coarctation. This model was validated by demonstrating that coarctation increased expression of the alpha-skeletal actin promoter 1.7-fold whereas the alpha-myosin heavy chain promoter was unaffected. Pressure overload increased expression from the AT1aR promoter by 1. 6-fold compared with controls. Mutations introduced into consensus binding sites for AP-1 or GATA transcription factors abolished the pressure overload response but had no effect on AT1aR promoter activity in control animals. In extracts from coarcted hearts, but not from control hearts, a Fos-JunB-JunD complex and GATA-4 were detected in association with the AP-1 and GATA sites, respectively. These results establish that the AT1aR promoter is active in cardiac muscle and its expression is induced by pressure overload, and suggest that this response is mediated, in part, by a functional interaction between AP-1 and GATA-4 transcription factors.

Animals↗
PubMed1997

Molecular cloning and heterologous expression of the isopullulanase gene from Aspergillus niger A.T.C.C. 9642.

Isopullulanase (IPU) from Aspergillus niger A.T.C.C. (American Type Culture Collection) 9642 hydrolyses pullulan to isopanose. IPU is important for the production of isopanose and is used in the structural analysis of oligosaccharides with alpha-1,4 and alpha-1,6 glucosidic linkages. We have isolated the ipuA gene encoding IPU from the filamentous fungi A. niger A.T.C.C. 9642. The ipuA gene encodes an open reading frame of 1695 bp (564 amino acids). IPU contained a signal sequence of 19 amino acids, and the molecular mass of the mature form was calculated to be 59 kDa. IPU has no amino-acid-sequence similarity with the other pullulan-hydrolysing enzymes, which are pullulanase, neopullulanase and glucoamylase. However, IPU showed a high amino-acid-sequence similarity with dextranases from Penicillium minioluteum (61%) and Arthrobacter sp. (56%). When the ipuA gene was expressed in Aspergillus oryzae, the expressed protein (recombinant IPU) had IPU activity and was immunologically reactive with antibodies raised against native IPU. The substrate specificity, thermostability and pH profile of recombinant IPU were identical with those of the native enzyme, but recombinant IPU (90 kDa) was larger than the native enzyme (69-71 kDa). After deglycosylation with peptide-N-glycosidase F, the deglycosylated recombinant IPU had the same molecular mass as deglycosylated native enzyme (59 kDa). This result suggests that the carbohydrate chain of recombinant IPU differed from that of the native enzyme.

Amino Acid Sequence↗