Search PubMed⌕ Search

Biomedical subjects

Y Aoki

Publications and source records attributed to Y Aoki.

At least 235 records · Page 13Linked to original sources
PubMed1999

Identification, by cDNA microarray, of A-raf and proliferating cell nuclear antigen as genes induced in rat lung by exposure to diesel exhaust.

Diesel exhaust particles (DEP) contain various carcinogens and mutagens, and chronic exposure to diesel exhaust (DE) induces pulmonary cancer in experimental animals. However, the oncogenes involved in pulmonary carcinogenesis have not been identified. After F344 rats were exposed to DE containing 6 mg/m3 DEP for 4 weeks, oncogenes and related genes expressed in their lungs were surveyed using a new technique, cDNA microarray, and the results were confirmed by northern blot analysis. Expression of A-raf and proliferating cell nuclear antigen (PCNA) mRNAs was induced in rat lung by exposure to DE. These results suggest that A-raf and PCNA might contribute to pulmonary carcinogenesis in rats.

Animals↗
PubMed1998

A human liver cell line exhibits efficient translation of HCV RNAs produced by a recombinant adenovirus expressing T7 RNA polymerase.

An in vitro system that supports the efficient growth of hepatitis C virus (HCV) and reflects its complete in vitro replication cycle has not yet been established. The establishment of a minigene RNA of HCV in mammalian cells could facilitate the study of virus-cell interactions and the molecular pathogenesis of this virus. We constructed a replication-deficient recombinant adenovirus expressing bacteriophage T7 RNA polymerase under the control of CAG promoter (AdexCAT7). A high level of T7 RNA polymerase was detectable for at least 11 days after inoculation. Cells infected with AdexCAT7 were then transfected with plasmids carrying the authentic T7 promoter, the 5' untranslated region (UTR) of encephalomyocarditis virus, a luciferase gene, and a T7 terminator (pT7EMCVLuc) or carrying the modified T7 promoter, the 5'UTR of HCV, a luciferase gene, the coding region of C-terminal of NS5B and the 3'UTR of HCV, a ribozyme of hepatitis D virus and a T7 terminator (pT7HCVLuc). Most of the cell lines examined supported a higher expression of luciferase by transfection with pT7EMCVLuc than with pT7HCVLuc. However, one cell line, FLC4, derived from a human hepatocellular carcinoma, exhibited very high reporter gene expression with pT7HCVLuc. In this cell line, transfection with RNA synthesized in vitro from pT7HCVLuc induced a higher level of reporter gene expression than RNA from pT7EMCVLuc. The T7-adenovirus system for the synthesis of HCV minigenes in vivo provides useful information on the molecular mechanisms of HCV translation in human liver cells.

3' Untranslated Regions↗
PubMed1998

New platelet fibrinogen receptor glycoprotein IIb-IIIa antagonists: orally active series of N-alkylated amidines with a 6,6-bicyclic template.

The design, synthesis, and pharmacological evaluation of (S)-(-)-ethyl [6-[4-(morpholinoformimidoyl)benzamido]-3, 4-dihydro-2H-1-benzopyran-3-yl]acetate hydrochloride ((S)-4.HCl, MS-180), an orally active glycoprotein IIb-IIIa (GPIIb-IIIa) antagonist, are reported. Pharmacophore mapping of amidino and carboxyl groups of already known GPIIb-IIIa antagonists led to the synthesis of nine amidino acids containing 6,6-bicyclic ring skeletons (10a-i). Among them, the compounds 10a,c,e having an amide bond and 1,2,3,4-tetrahydronaphthalene or 3, 4-dihydro-2H-1-benzopyran skeleton showed marked inhibitions with IC50 values of 46-57 nM in human platelet aggregation assay in vitro, but low oral activities. N-Alkylation of the amidino group coupled with the ester prodrug approach afforded MS-180 ((S)-4.HCl), which generates in vivo the corresponding carboxylic acid (S)-3 as an active species. In vitro, (S)-3 inhibited ADP-induced aggregation of guinea pig, dog, and human platelets (IC50 = 110, 253, and 35 nM, respectively) and inhibited the binding of fibrinogen to immobilized GPIIb-IIIa of human platelets (IC50 = 0.12 nM). After oral administration of MS-180 ((S)-4.HCl) to fasted beagle dog, ex vivo inhibition of platelet aggregation was observed. The maximal inhibitions were observed 2-4 h after dosing with dose dependency (60% inhibition at a dose of 1 mg/kg, 85% at 3 mg/kg, and 100% at 10 mg/kg, respectively) and the extent of the inhibitions paralleled the plasma concentration of the active species (S)-3. On the basis of these studies, we selected MS-180 ((S)-4.HCl) as a candidate for clinical evaluation as a drug for the treatment and prevention of thrombosis in patients.

Acetates↗
PubMed1998

Metallothionein deficiency promotes mouse skin carcinogenesis induced by 7,12-dimethylbenz[a]anthracene.

To investigate a possible involvement of metallothionein (MT) in chemical carcinogenesis, MT-I and MT-II gene-deficient [MT (-/-)] transgenic mice and wild-type [MT (+/+)] control mice were topically applied at a single dose of 100, 250, 500, or 1000 microg of 7,12-dimethylbenz[a]anthracene (DMBA) on the dorsal skin and thereafter compared. After 14 weeks of DMBA treatment, the skin tumor occurred in MT (-/-) mice only and in a dose-dependent manner, whereas no change was observed in MT (+/+) mouse skin given the same DMBA treatment. The tumor cells showed proliferative activity, as shown by proliferative cell nuclear antigen staining. These results demonstrate that MT acts as an endogenous defensive factor against DMBA-induced skin tumorigenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

Direct analysis of several Fusarium mycotoxins in cereals by capillary gas chromatography-mass spectrometry.

A method for qualitative and quantitative analysis of Fusarium mycotoxins by gas chromatography-mass spectrometry (GC-MS) using cold on-column injection was improved. Eight typical mycotoxins, including deoxynivalenol (DON), 3-acetyldeoxynivalenol (3ADN), fusarenon-X (FX), diacetoxyscirpenol (DAS), 15-monoacetylscirpenol (15MAS), T-2 toxin (T-2), scirpentriol (SCT), and zearalenone (ZEA) were subjected to GC-MS without chemical derivatization by means of the on-column injection technique. Chromatographic separation of the toxins extracted from barley was achieved as a single peak, and the specific EI mass spectra of each toxin were obtained. The fatty acids in the extract that interfere with measurements of the toxins on the gas chromatogram were removed by precipitation as an insoluble metal soap with zinc acetate. Additional clean-up was accomplished using a Bond Elut Florisil cartridge. The quantitative detection limit in barley ranged from 0.1 to 0.5 micrograms/g. The average recoveries of 93.1% for DON, 3ADN, 15MAS, DAS, T-2 and ZEA, and 46.0% for FX and SCT added to barley at the level of 1 microgram/g were obtained.

Calibration↗
PubMed1998

Identification of holocarboxylase synthetase (HCS) proteins in human placenta.

Holocarboxylase synthetase (HCS) is a key enzyme in biotin utilization in eukaryotic cells. In a previous work from our laboratory, we described the cloning and sequencing of a full-length human HCS cDNA. Due to the presence of three candidate sites for initiation of translation, the identification of full-length HCS proteins remains uncertain. Using antibodies directed against human HCS sequences, we have identified, in human placenta, three cytosolic HCS proteins, of 86, 82 and 76 kDa. Similar results were observed in lysates of cells transfected with an HCS expression vector, as well as with human HCS cDNA transcribed and translated in a cell-free system. When anti-HCS antibodies were tested for their ability to inhibit HCS enzymatic activity, only the antibody directed against a region of HCS from Ile128 to Pro398, and not the antibodies against more proximal N-terminal regions inhibited HCS activity, suggesting that the sequence from Ile128 to Pro398 is essential for the catalytic activity of this enzyme. HCS synthesized in a cell-free system was not translocated into rat liver mitochondria. These results suggest that our human HCS cDNA encodes the cytosolic forms of the enzyme. These results also suggest that mRNA encoding cytosolic HCS can be translated from all three translation initiation codons, Met1, Met7 and Met58.

Animals↗
PubMed1998

Establishment and characterization of a murine osteosarcoma cell line (LM8) with high metastatic potential to the lung.

We established a murine osteosarcoma cell line (LM8) with high metastatic potential to the lung from murine Dunn osteosarcoma using 8 repeated Fidler's procedures. We performed the biological characterization of the LM8 and the maternal Dunn cell lines in vitro and in vivo. Morphologically, LM8 possesses many fillopodial protrusions, lamellipodial structures surrounding the cell surface and membrane ruffles suggesting enhanced cell motility. The increased matrix metalloproteinase (MMP) 2 activity of this cell line might help cell invasion after penetration of the endothelial (mesothelial) cell layer. This cell line exhibited high in vitro invasive activity when seeded onto the mesothelial cell monolayer. Higher expression of VEGF mRNA in this cell line might facilitate neovascularization at the site of metastasis, resulting in extremely high metastatic potency after i.v. injection. LM8 also showed a high metastatic incidence (7/7) to the lung even after s.c. transplantation into the back space of mice. This cell line can provide an excellent tool for studying inhibitory agents against pulmonary metastasis as well as the various important factors involved in metastasis of osteosarcoma.

Alkaline Phosphatase↗
PubMed1998

High-dose conformal radiotherapy influenced the pattern of failure but did not improve survival in glioblastoma multiforme.

BACKGROUND AND PURPOSE: Although glioblastoma multiforme is clearly radiation-resistant, there is evidence of a dose-dependent response relationship. The purpose of the study was to evaluate the impact of higher dose by rotational multileaf collimator (MLC) conformal radiation therapy. MATERIALS AND METHODS: From 1984 to 1995, 38 consecutive cases with intracranial glioblastoma multiforme were treated using the rotational MLC conformal therapy. There were 25 men and 13 women with a median age of 47 years (12-73 years, mean 46.5 years). Median Karnofsky performance score was 80 (30-100, mean 78.2). Median tumor volume was 64 cc (8-800 cc, mean 110.3 cc). All underwent surgical intervention (only biopsy in 1, partial resection in 13, subtotal resection in 21, and gross total resection in 3). Radiation dose to was 60 to 80 Gy (median 68.5 Gy, mean 68.3 Gy) in 21 patients treated before 1990 and 90 Gy in the 17 patients thereafter. Biweekly i.v. chemotherapy was also administered for both arms. RESULTS: The 1-year, 2-year, 5-year, and 10-year overall survival rates were 75%, 42%, 20%, and 15%, respectively. Univariate analysis showed the initial tumor volume, residual tumor volume, and Karnofsky performance score were statistically significant factors for survival. Only the residual tumor volume was statistically significant by multivariate analysis. The 5-year survival rate of patients with residual tumors of 5 cc or less in volume was as good as 37%. Survival of the 90-Gy Group appeared inferior to that of the Low-Dose Group, though no statistical difference was seen (the 3-year survival was 40% vs. 22%). Local failure was observed in 16 of the 19 recurrences in the Low-Dose Group, whereas it was observed in only 4 of the 13 recurrences in the 90-Gy Group. The difference in pattern of failure was statistically significant. Two patients of the High-Dose Group developed radiation necrosis and one died of it. CONCLUSIONS: The high-dose conformal radiotherapy did not improve survival in the disease, but did change the pattern of failure.

Adolescent↗
PubMed1998

Coordinate regulation of STAT signaling and c-fos expression by the tyrosine phosphatase SHP-2.

The src homology 2 (SH2) domain-containing protein-tyrosine phosphatase SHP-2 has been implicated as an important positive regulator of several mitogenic signaling pathways. SHP-2 has more recently been shown to be tyrosine phosphorylated and recruited to the gp130 component of the ciliary neurotrophic factor (CNTF) receptor complex upon stimulation with CNTF. CNTF does not, however, have a proliferative effect on responsive cells, but rather enhances the survival and differentiation of sympathetic, motor, and sensory neurons. In this study, expression of an interfering mutant of SHP-2 in the neuroblastoma cell line NBFL increased CNTF induction of a vasoactive intestinal peptide (VIP) reporter gene, and in cultures of sympathetic neurons, it resulted in an up-regulation of endogenous VIP and substance P (SP) gene expression. Members of the CNTF family of cytokines transmit their signal by activating signaling pathways involving both STAT and Fos-Jun transcription factors. In CNTF-stimulated NBFL cells that constitutively express the SHP-2 interfering mutant, there was increased and prolonged formation of STAT/DNA complexes, but decreased AP-1 binding activity, that mirrored a down-regulation of c-fos expression both at the mRNA and protein level. Taken together, these data indicate that SHP-2 has dual and opposing roles in a signaling cascade triggered by the same ligand, as illustrated by its ability to differentially regulate the levels of activity of both STAT and AP-1 transcription factors.

Animals↗
PubMed1998

Two CPT2 mutations in three Japanese patients with carnitine palmitoyltransferase II deficiency: functional analysis and association with polymorphic haplotypes and two clinical phenotypes.

Carnitine palmitoyltransferase II (CPT II) deficiency manifests as two different clinical phenotypes: a muscular form and a hepatic form. We have investigated three nonconsanguineous Japanese patients with CPT II deficiency. Molecular analysis revealed two missense mutations, a glutamate (174)-to-lysine substitution (E174K) and a phenylalanine (383)-to-tyrosine substitution (F383Y) in the CPT II cDNA. Transfection experiments in COS-1 cells demonstrated that the two mutations markedly decreased the catalytic activity of mutant CPT II. Case 1 (hepatic form) was homozygous for the F383Y mutation, whereas case 3 (muscular form) was homozygous for the E174K mutation. Case 2 and her brother, who were compound heterozygotes for E174K and F383Y, exhibited the hepatic phenotype. We also identified a novel polymorphism in the CPT2 gene, a phenylalanine (352)-to-cysteine substitution (F352C), which did not alter CPT II activity in transfected cells. It was present in 21 out of 100 normal alleles in the Japanese population, but absent in Caucasian populations. Genotyping with the F352C polymorphism and the two previously reported polymorphisms, V368I and M647V, allowed normal Japanese alleles to be classified into five haplotypes. In all three families with CPT II deficiency, the E174K mutation resided only on the F1V1M1 allele, whereas the F383Y mutation was observed on the F2V2M1 allele, suggesting a single origin for each mutation.

Adult↗
PubMed1998

Full-length complementary DNA of hepatitis C virus genome from an infectious blood sample.

We constructed a full-length complementary DNA (cDNA) clone of hepatitis C virus (HCV) from a blood sample of an HCV carrier. The blood from the carrier was eventually transfused to a patient who later developed typical posttransfusion hepatitis C. It was also shown to be infectious to chimpanzees. We obtained 12 overlapping cDNA fragments altogether, covering the entire HCV genome. By subcloning and sequencing, clones considered to constitute the major population were selected. We could also detect 98 base pairs of extra sequences at the 3' end of the genome. After confirming the overlapping sequences, we combined the fragments to make a full-length cDNA. The HCV population in the donor was heterogeneous, as determined by their nucleotide sequences of the hypervariable region in envelope protein, but a few virus clones were selected in the recipient after transmission. The similar convergence of the virus population was previously observed when the same blood sample was injected into a chimpanzee. Interestingly, virus clones isolated during the acute phase in the recipient and the chimpanzee had sequences in the hypervariable region identical to that of the full-length cDNA clone. The full-length cDNA clone of HCV constructed in this study may originate from infectious virus clones.

Amino Acid Sequence↗
PubMed1998

Stimulation of G-CSF gene expression in the macrophage cell line by contact with extracellular matrix proteins and a pre-B leukaemia cell line.

In order to scrutinize the adherence-dependent interactions for induction of granulocyte colony-stimulating factor (G-CSF) in peripheral monocytes/macrophages, a sensitive reporter gene assay was constructed using the mouse macrophage cell line transfected with the mouse G-CSF promoter region in conjunction with the luciferase gene as a reporter. With this system, lipopolysaccharide (LPS) showed a markedly positive response. Among the extracellular matrix (ECM) proteins, both fibronectin (FN) and vitronectin (VN) markedly induced luciferase activity, but others did so but much lesser extent. Among the synthetic peptides having Arg-Gly-Asp (RGD) sequences, only FLEPP with multiple RGD significantly induced luciferase activity. Pretreatment of the cells with anti-integrin alpha 6, alpha M, beta 1 and beta 2 monoclonal antibodies (mAbs) significantly reduced the LPS-induced responses and anti-alpha 1, alpha 2 and beta 3 mAbs to lesser extent, and anti-alpha 5, alpha 6, alpha M, beta 1 and beta 2 mAbs blocked the FN-induced response. In the cell-to-cell interactions, significantly positive increase was observed by direct contacting this cell line with a G-CSF-dependent promyelocytic leukaemia cell line, known to stimulate the induction of G-CSF to the stromal cells. Its effect was mostly blocked by pretreatment with anti-integrin alpha 5, alpha L, beta 1 and beta 2 and anti-ICAM-1 mAbs. These results indicate that there are several pathways via the cell-to-ECM and cell-to-cell interactions triggering the induction of G-CSF in the macrophages.

Animals↗
PubMed1998

Efficacy of ivermectin against Strongyloides stercoralis infection in jirds (Meriones unguiculatus).

The activity and distribution of ivermectin (IVM), a broad spectrum anthelmintic for various nematodes and arthropods, was tested against Strongyloides stercoralis infection in the jird (Meriones unguiculatus.) The pattern of IVM concentration in the serum of jirds after either low- (200 microg/kg) or high-dose (1000 microg/kg) treatment by intraperitoneal injection showed a typical single-peak profile with the maximum drug levels detected at 1 h followed by a rapid decline to undetectable values by 48 h posttreatment. With equivalent IVM doses, the serum levels in male jirds were significantly higher than those observed in female jirds at 1 and 12 h posttreatment (P < 0.05). Low-dose IVM treatment of either male or female jirds, in comparison with that of the respective control groups, produced no observable effect on the adult worm burden or the parasite fecundity. The curative dose for S. stercoralis in both sexes of animals was achieved when using the high dose of 1000 microg/kg of IVM. The area under the curve calculated from the serum-concentration profiles in males was significantly higher than that for females after the high-dose treatment of IVM (P < 0.05). By low-dose treatment, a significantly lower adult worm burden was observed in males compared with that in females (P < 0.05), and this difference correlated with the higher serum levels of IVM in male animals. The distribution of IVM in the jird after high-dose treatment was characterized by initial appearances at 1 h of maximum levels of the drug in the serum and intestinal content. The maximum level in the feces was reached at 12 h posttreatment and rapidly declined thereafter. The level in the intestinal tissue was comparatively much lower than that in the intestinal content and the feces. The half-life of IVM in the intestinal content (49.5 h) was longer than those in the serum, feces, and intestinal tissue (6.53-13.07 h). Analyses of the relationship between the peak serum IVM occurring at 1 h posttreatment and the adult worm recovery revealed that the minimal serum concentration associated with clearance of the adult worm from the jird was approximately 0.65 microg/ml. The jird-S. stercoralis model has not only made studies on various aspects of parasite biology possible, but also provided an in vivo system to examine the efficacy as well as the mode of action of IVM against this intestinal nematode.

Animals↗
PubMed1998

Radiotherapy of bone metastases of a spinal meningeal hemangiopericytoma.

Hemangiopericytoma is a rare tumor arising from pericapillary cells or pericytes of Zimmerman, and can occur anywhere capillaries are found. We describe a patient with a meningeal hemangiopericytoma who was treated with primary surgical resection and experienced multiple bone metastases 20 years after the first treatment. This patient with multiple bone metastases was treated with multiple courses of irradiation and good palliation was achieved.

Adult↗
PubMed1998

Role of medullasin in nifedipine-induced gingival overgrowth in rats.

To clarify the possible pathophysiological role of medullasin, a neutrophil elastase-like proteinase, in nifedipine (NF)-induced gingival overgrowth, a rat model of gingival overgrowth was first established using a diet containing NF. The relation between histopathological changes and the distribution of the proteinase was then investigated. Thirty-two, specific pathogen-free 20 day-old, male, Fisher 344 rats were fed a diet containing NF and killed at 2, 8, 16 and 32 weeks. Control rats (n = 32) were fed the same diet but without the drug. The mandible of each rat was resected and sectioned at 4-microm thickness buccolingually between the first and second molars. Computer image analysis was used to evaluate the extent of overgrowth in the approximal gingiva of each sample. To examine medullasin activity, the mean percentage of medullasin-positive cells per total cells counted in the pocket epithelium and the connective tissue adjacent to the epithelium of approximal gingiva was determined immunohistochemically. The height of the mid-portion and the area in NF-treated group increased significantly with time (with the exception of area at 2 weeks) compared with the corresponding regions in the control group. A marked inflammatory-cell infiltration and elongated rete pegs, especially in the mid-portion of approximal gingiva, were seen in the NF-treated group. The mean percentages of medullasin-positive cells in the NF-treated group at 8, 16 and 32 weeks were significantly higher than those of the control. Although medullasin-positive cells were mainly neutrophils, in several samples of the NF-treated group they were recognized as macrophage-like. These findings suggest that medullasin may be involved in host defence and immunoregulation in a NF-induced rat model of gingival overgrowth.

Animals↗
PubMed1998

A direct competitive ELISA for the simple, sensitive and accurate determination of diethylcarbamazine concentration in serum.

Improved methods for measurement of the anti-filariasis drug diethylcarbamazine in serum would assist in the design of effective therapy. The method evaluated in the present paper is a direct competitive ELISA which is sensitive, specific and accurate. Horseradish peroxidase-labelled diethylcarbamazine conjugate was incubated with diethylcarbamazine and anti-diethylcarbamazine antiserum over a bound second antibody. The enzyme activity of the remaining diethylcarbamazine-horseradish peroxidase conjugate was measured. The intra- and inter-assay coefficient of variation was < 10% in the range of 1.0-30 ng ml-1 and the limit of detection was 0.3 ng ml-1. The cross reactivities of anti-diethylcarbamazine antibodies with diethylcarbamazine metabolites and ivermectin were < 0.09%. Using the ELISA, the serum levels of diethylcarbamazine were successfully determined in mongolian jirds (Meriones unguiculantus) up to 4h following a single dose of 50 mg kg-1 of body weight. The values of pharmacokinetic parameters of diethylcarbamazine in jirds were determined.

Animals↗
PubMed1998

Interstitial laser coagulation for management of benign prostatic hyperplasia: a Japanese experience.

PURPOSE: The principle of interstitial laser coagulation is to shrink the prostate by generating intraprostatic necrosis without damaging the urethra or causing tissue sloughing. The clinical efficacy and durability of interstitial laser coagulation in the treatment of benign prostatic hyperplasia (BPH) were evaluated. MATERIALS AND METHODS: From December 1993 to June 1996, 76 patients with symptomatic BPH were treated with interstitial laser coagulation. A neodymium:YAG laser was used in combination with a specially designed interstitial thermotherapy light guide. The tip of the light guide was inserted into each lobe of the prostate transurethrally under direct vision. All evaluations were made at baseline and then 1, 3, 6 and 12 months after therapy. Treatment outcome was evaluated by International Prostate Symptom Score (I-PSS), flow rate and post-void residual urine volume. Disease specific quality of life was assessed via a quality of life assessment score and a BPH impact index. Independent of symptom assessment, a self-reporting questionnaire was prepared at 3 months postoperatively regarding satisfaction with treatment and sexual function. RESULTS: Among 44 patients followed to 12 months the mean I-PSS significantly decreased from 20.4 at baseline to 7.4, representing 64% improvement (p <0.001). Peak flow rate increased by 50% from a preoperative average of 7.4 to 11.1 ml. per second at 12 months in 42 patients (p <0.001). The post-void residual volume decreased by 57% from 102 to 44 ml. at 12 months in 40 cases (p <0.001). Steady and progressive improvement was observed on quality of life assessment and BPH impact index scores at 3, 6 and 12 months. No patients reported new onset of erectile dysfunction. No serious side effects were observed, except for loss of ejaculation in 3 cases and seminal vesicle abscess in 1. Only 6 patients (8%) required re-treatment for persisting obstructive symptoms during 12 months of followup. A recent change in methods towards more aggressive treatment plausibly influenced the outcomes to require less repeat treatment. CONCLUSIONS: After the interstitial laser coagulation procedure satisfactory results were obtained and improvement lasted through 12 months. Although the optimal number of fiber placements for each prostate is not known, more aggressive treatment appears to provide better outcomes.

Aged↗