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Biomedical subjects

Y Fujiwara

Publications and source records attributed to Y Fujiwara.

At least 361 records · Page 20Linked to original sources
PubMed1995

Isolation of a candidate tumor suppressor gene on chromosome 8p21.3-p22 that is homologous to an extracellular domain of the PDGF receptor beta gene.

We have isolated a candidate tumor suppressor gene from a 600-kb region on chromosome 8p21.3-p22 that is commonly deleted in sporadic hepatocellular carcinomas (HCC), colorectal cancers (CRC), and non-small cell lung cancers (NSCLC). As this gene encodes a protein of 375 amino acids that bears significant sequence similarity to the extracellular (ligand-binding domain of platelet-derived growth factor receptor beta, we have designated it PRLTS (PDGF-receptor beta-like tumor suppressor). Structural rearrangement involving this gene was found in a sporadic NSCLC. In addition, somatic missense and frame-shift mutations were found in two HCCs and one CRC. These findings indicate that inactivation of the PRLTS gene may play a significant role in development of some carcinomas.

Amino Acid Sequence↗
PubMed1995

Inhibitory effect of lead on the proliferation of cultured vascular endothelial cells.

We investigated the effect of lead nitrate (0.5, 1.0, 2.0 or 5.0 microM) on the proliferation of cultured bovine aortic endothelial cells. After exposure to lead, the number of cells and the incorporation of [3H]thymidine into the acid-insoluble fraction of the cells were reduced in parallel in a concentration-dependent manner. Histologically, lead treatment resulted in a decrease in the cell number accompanied by a change in the cell shape from polygonal to spindle; however, no degenerative change was observed except in 5.0 microM lead-treated cells. Furthermore, stimulation of [3H]thymidine incorporation by either basic or acidic fibroblast growth factor was significantly reduced by lead. However, the leakage of lactate dehydrogenase into the medium from the cells, a marker of nonspecific cell damage, was not changed by lead. From these results, it was revealed that lead inhibits the proliferation of cultured vascular endothelial cells without nonspecific cell damage. Although lead does not destroy the monolayer of endothelial cells, the metal may exhibit its noxious effect in the repair process of the vascular endothelium.

Animals↗
PubMed1995

Accumulation of genetic changes during development and progression of hepatocellular carcinoma: loss of heterozygosity of chromosome arm 1p occurs at an early stage of hepatocarcinogenesis.

To investigate cumulative genetic changes during development and progression of hepatocellular carcinoma (HCC), we examined DNAs isolated from 104 tumors for loss of heterozygosity (LOH) at 13 loci on six chromosomal arms and for an increase of copy number ("multiplication") of alleles on 8q, using polymorphic microsatellite markers. A comparison of genetic features with clinicopathological stages of these tumors revealed that LOH on 1p had occurred in tumors at an early stage or with a well-differentiated histological phenotype (8/26; 31%) as well as in tumors at more advanced stages. Genetic alterations on chromosome arms 4q, 8p, 8q, 13q, 16q, and 17p were more often observed in tumors of more advanced stages and poorer differentiation grades. When size was the criterion for comparison, LOH on 1p was observed frequently even in tumors smaller than 2 cm (6/16; 38%), whereas allelic losses on 16q were detected frequently only in larger tumors. These results suggest that the putative tumor suppressor gene(s) assumed to be located on 1p may be involved in an early step of carcinogenesis in liver tissue and that the other genetic alterations examined here may play important roles in progression of HCC.

Carcinoma, Hepatocellular↗
PubMed1995

Localization of a tumor suppressor gene associated with progression of human prostate cancer within a 1.2 Mb region of 8p22-p21.3.

Human prostate cancers frequently show loss of heterozygosity at loci on the short arm of chromosome 8. In order to take a step toward isolation of the putative tumor suppressor gene(s) on 8p via positional cloning, we performed high-resolution deletion mapping in 46 prostate cancers (stage B, 20 cases; stage C, 8 cases; endocrine therapy-resistant cancer death, 18 cases) using new 12 restriction fragment length polymorphism markers for this chromosomal region. Allelic losses were observed in 25 of the 44 cases (57%) that were informative with at least one locus. Detailed deletion mapping defined a 1.2 Mb commonly deleted region at 8p22-p21.3 flanked by markers cMSR-32 and C18-1051. A second region of common deletion was identified between C18-1312 and C18-494 at 8p21-8p11.22, suggesting that at least two tumor suppressor genes associated with prostate cancer are present on chromosome arm 8p. Allelic losses on 8p were observed more frequently in the cancer death cases (14/17, 82%) than in early-stage tumors (11/27, 40%; P < 0.01, Fisher's exact test). In two out of 7 patients for whom DNA was available from metastatic cancers as well as from normal tissues and primary tumors, the primary cancer foci had no detectable abnormality of 8p, but the metastatic tumors showed loss of heterozygosity. These results suggest that inactivation of tumor suppressor genes on 8p plays an important role in the progression of prostate cancer.

Adenocarcinoma↗
PubMed1995

Biosynthetic transport of a major lysosomal membrane glycoprotein, lamp-1: convergence of biosynthetic and endocytic pathways occurs at three distinctive points.

We studied the kinetics of the biosynthetic transport of lysosome-associated membrane glycoprotein-1 (lamp-1) to the endocytic compartments in cultured rat hepatocytes. Newly synthesized lamp-1 (NS-lamp-1) was transported to the trans-Golgi from rough endoplasmic reticulum with a half time (t1/2) of 13 min. From the trans-Golgi, at least 25% of NS-lamp-1 was delivered to the cell periphery: to the cell surface and early endosomes with t1/2 s of 32 and 33 min, respectively. A comparison of the kinetics of the biosynthetic transport of lamp-1 to both compartments demonstrated that NS-lamp-1 takes two peripheral routes from the Golgi apparatus; it is delivered to early endosomes directly and after reaching the cell surface. A major portion of NS-lamp-1 follows a direct intracellular pathway to late endosomes (t1/2 = 45 min) and subsequently to lysosomes (t1/2 = 85 min). The kinetic data of the biosynthetic transport to these endocytic vacuoles suggested that a significant fraction of NS-lamp-1 returns to the late endosomes immediately after its arrival at lysosomes and that there is a unique retrograde delivery of NS-lamp-1 from late to early endosomes prior to its transport to lysosomes. Thus, in cultured rat hepatocytes, the lamp-1 biosynthetic and the endocytic pathways converge at the three distinctive points. Late endosomes are centrally situated in the complex biosynthetic route of lamp-1.

Animals↗
PubMed1995

Induction of apoptosis in cultured retinoblastoma cells by the protein phosphatase inhibitor, okadaic acid.

The induction of apoptosis in cultured retinoblastoma cells by diverse drugs was examined by analyzing DNA fragmentation, a hallmark of apoptosis. First, the ability of six retinoblastoma cell lines to undergo apoptosis was surveyed using etoposide (30 micrograms/ml, 20 h exposure). The NCC-RbC-60 cell line, established in this laboratory showed DNA fragmentation clearly, whereas the other cell lines tested, including the representative retinoblastoma cell line, Y-79, did not show distinct DNA fragmentation. Biochemical modulators, such as A23187, forskolin, retinoic acid, phorbol 12-myristate 13-acetate and okadaic acid, were examined to ascertain whether they could induce apoptosis in NCC-RbC-60 and Y-79 cells after exposure for 20 h. Only okadaic acid induced DNA fragmentation in all the retinoblastoma cell lines tested and it induced DNA fragmentation in Y-79 cells in a time- and concentration-dependent manner. Flow-cytometric analysis and microscopic examination revealed that Y-79 cells treated with okadaic acid for 24-48 h accumulated at the G2/M, especially M, phases, before undergoing DNA fragmentation. Other mitotic poisons, nocodazole, colcemid and taxol, also induced apoptosis in Y-79 cells. In the K1034 cell line, established from non-malignant retinal pigmented epithelium, okadaic acid failed to induce both G2/M arrest and DNA fragmentation. These findings suggest that okadaic-acid-induced apoptosis occurs as a result of metaphase arrest.

Apoptosis↗
PubMed1995

Ontogeny of behavioral sensitization to cocaine.

The ontogeny of the behavioral effects of acute cocaine administration and behavioral sensitization to cocaine in rat pups was investigated. Acute behavior stimulating effects of cocaine were observed in pups as young as 7 postnatal days (PND) old, although they needed a higher dose of cocaine than adult rats to evoke the same motor effects. An adult dose-response curve pattern of stereotypy and locomotion to acute cocaine treatment was observed at PND 21, and of rearing at PND 28. Rats aged PND 7, 14, 21, 28, and 56 received repeated injections of saline or cocaine (15 mg/kg) twice a day for 5 consecutive days. After a 3-week period of abstinence, sensitization to a challenge dose of cocaine was assessed. Cocaine-induced stereotyped behavior was enhanced significantly only in rats in which cocaine pretreatment was initiated on PND 21, 28, and 56, but not earlier on PND 7 and 14. Adult female rats given repeated cocaine injections on PND 56-60 showed significantly greater sensitization than males, but no such sex difference was observed in pups given cocaine repeatedly on PND 21-25 or 28-32. These results show clearly that cocaine-induced behavioral sensitization in rats occurred only when subchronic cocaine administration was commenced on PND 21 or later.

Animals↗
PubMed1995

Evidence for the presence of two tumour-suppressor genes for hepatocellular carcinoma on chromosome 13q.

The concept that genetic changes accumulate during development and progression of cancer is widely accepted. Frequent allelic losses at chromosome 13q have been found in hepatocellular carcinomas (HCCs), and a known tumour-suppressor at 13q14, the retinoblastoma (RB) gene, is thought to be the target of those events. However, no strong evidence has emerged to support a significant role of RB during hepatocarcinogenesis. To investigate the minimal area(s) of loss on chromosome 13q in HCCs, we analysed DNAs isolated from 92 tumours for loss of heterozygosity (LOH) at 13 loci on chromosome 13q, using polymorphic microsatellite markers. In 30 (32.6%) of 92 cases we detected LOH for at least one locus on chromosome 13q and 20 revealed a partial or interstitial deletion of chromosome 13q. Deletion mapping of these 20 tumours indicated two separate commonly deleted regions: one was located in the region including RB and the other was located in the region including the BRCA2 locus. These findings suggest that at least one putative tumour-suppressor gene for HCC other than RB, possibly BRCA2, exists on chromosome 13q.

BRCA1 Protein↗
PubMed1995

Phase I study and clinical pharmacological evaluation of daily oral etoposide combined with carboplatin in patients with lung cancer.

Twenty-eight patients with inoperable or relapsed lung cancer were given a combination of oral etoposide, administered once a day at doses ranging from 40 to 60 mg/m2/day (d) for 21 consecutive days, and carboplatin, administered intravenously over 1 h at doses ranging from 300 to 400 mg/m2 on day 1 to determine the appropriate doses of this combination. In addition, pharmacokinetic and pharmacodynamic analyses were performed. All the patients had a performance status of 0 to 1. Serum etoposide and free platinum (Pt) concentrations were measured using high-performance liquid chromatography and atomic absorption, respectively. Myelosuppression, nausea and vomiting were the dose-limiting toxicities of this schedule. The maximum tolerated dose (MTD) was 50 mg/m2/d oral etoposide for 21 days and 400 mg/m2 i.v. carboplatin on day 1. For heavily pretreated patients, the MTD was 40 mg/m2/d oral etoposide for 21 days and 350 mg/m2 i.v. carboplatin on day 1. No cumulative increase in the area under the concentration-time curve (AUC) for oral etoposide over time was observed. There were significant correlations between the free Pt serum level (6, 8, 12, 24 h post-dose) and etoposide AUC level (days 1, 10 and 21) for graded hematological toxicity, and the percentage decreases and nadir counts of hemoglobin, leukocytes, neutrophils and platelets. Several pharmacodynamic models were developed to predict the hematological toxicity. In order to facilitate pharmacodynamic evaluations in future studies, a limited sampling model for oral etoposide was also developed and validated.

Administration, Oral↗
PubMed1995

Photochemistry of acetylenic ketones in micellar solutions as studied by product-yield-detected ESR and transient absorption techniques.

The electron spin resonance (ESR) spectra of the transient radical pairs in the photoreduction of 1,5-diphenyl-1,4-pentadiyn-3-one(I) and 1,3-diphenyl-2-propyn-1-one(II) in sodium dodecyl sulfate (SDS) micellar solutions have been obtained by using the product-yield-detected ESR (PYESR) technique. The PYESR spectra, detected by tracing the microwave effect on the spin-adduct yield as functions of the magnetic field, show the ESR spectra of the ketyl radical of the ketone and SDS radical as the components of the radical pairs. In addition, the growth and the decay processes of the radical pair were observed through detecting the effect of microwave pulse as functions of the delay period between a laser pulse and the off and on time, respectively, of a microwave pulse. The absorption spectra of transient species have also been obtained by using the laser flash photolysis technique. Through the analysis of these data and molecular orbital calculations, the role of acetylenic groups in the photoreactivity of acetylenic ketones is discussed.

Alkynes↗
PubMed1995

Indomethacin interferes with epidermal growth factor binding and proliferative response of gastric KATO III cells.

Indomethacin induces gastric ulcerations and decreases cell proliferation in the gastric ulcer margin. Since epithelial cell proliferation is under control of epidermal growth factor (EGF), we studied whether indomethacin may affect specific binding of [125I]-EGF to its receptors in cultured human gastric KATO III cells. To assess effects of EGF, indomethacin and their combination on cell proliferation, KATO III cells were incubated for 24 h with either (a) vehicle (b) indomethacin (doses from 10(-5) to 10(-3) M), EGF (doses 0.01, 0.05 or 0.1 microgram/ml) or (d) a combination of b and c, and the bromodeoxyuridine labeling index was determined. Indomethacin in a dose which did not affect cell viability significantly (by 21.5%) decreased [125I]-EGF binding to the KATO III cells and decreased the bromodeoxyuridine labeling index. Epidermal growth factor significantly increased cell proliferation and increased the labeling index from 28.9 +/- 0.6% in the vehicle group to 36.2 +/- 0.5%. Co-treatment with indomethacin significantly reduced the proliferative response of KATO III cells to EGF. In conclusion, indomethacin, in a dose which does not affect cell viability, decreased binding of EGF to cultured gastric KATO III cells and decreased their proliferative response to EGF.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1995

Facial nerve paralysis induced by herpes simplex virus in mice: an animal model of acute and transient facial paralysis.

We have been the first to succeed in producing an acute and transient facial paralysis simulating Bell's palsy, by inoculating herpes simplex virus into the auricles or tongues of mice. The KOS strain of the virus was injected into the auricle of 104 mice and the anterior two thirds of the tongue in 30 mice. Facial paralysis developed between 6 and 9 days after virus inoculation, continued for 3 to 7 days, and then recovered spontaneously. The animals were painlessly sacrificed between 6 and 20 days after inoculation for histopathologic and immunocytochemical study. Histopathologically, severe nerve swelling, inflammatory cell infiltration, and vacuolar degeneration were manifested in the affected facial nerve and nuclei. Herpes simplex virus antigens were also detected in the facial nerve, geniculate ganglion, and facial nerve nucleus. The pathophysiologic mechanisms of the facial paralysis are discussed in light of the histopathologic findings, in association with the causation of Bell's palsy.

Animals↗
PubMed1995

Vascular endothelial cell lineage-specific promoter in transgenic mice.

Vascular endothelial cells play essential roles in the function and development of the cardiovascular system. However, due to the lack of lineage-specific markers suitable for molecular and biochemical analyses, very little is known about the molecular mechanisms that regulate endothelial cell differentiation. We report the first vascular endothelial cell lineage-specific (including angioblastic precursor cells) 1.2 kb promoter in transgenic mice. Moreover, deletion analysis of this promoter region in transgenic embryos revealed multiple elements that are required for the maximum endothelial cell lineage-specific expression. This is a powerful molecular tool that will enable us to identify factors and cellular signals essential for the establishment of vascular endothelial cell lineage. It will also allow us to deliver genes specifically into this cell type in vivo to test specifically molecules that have been implicated in cardiovascular development. Furthermore, we have established embryonic stem (ES) cells from the blastocysts of the transgenic mouse that carry the 1.2 kb promoter-LacZ reporter transgene. These ES cells were able to differentiate in vitro to form cystic embryoid bodies (CEB) that contain endothelial cells determined by PECAM immunohistochemistry. However, these in vitro differentiated endothelial cells did not express the LacZ reporter gene. This indicates the lack of factors and/or cellular interactions which are required to induce the expression of the reporter gene mediated by this 1.2 kb promoter in this in vitro differentiation system. Thus this system will allow us to screen for the putative inducers that exist in vivo but not in vitro. These putative inducers are presumably important for in vivo differentiation of vascular endothelial cells.

Animals↗
PubMed1995

Stimulation of cultured vascular smooth muscle cell proliferation by thrombospondin is potentiated by zinc.

The interaction of zinc sulfate with thrombospondin (TSP) derived from bovine platelets, on the proliferation of bovine aortic smooth muscle cells was investigated using cell culture. Zinc alone has no effect but potentiates the stimulatory effect of TSP on the incorporation of [3H]thymidine into the acid-insoluble cell fraction. Other heavy metals including copper, lead, manganese and nickel did not exhibit a similar effect. In bovine aortic endothelial cells, [3H]thymidine incorporation was stimulated by zinc alone and suppressed by TSP alone; the stimulation by zinc was significantly reduced by TSP. In human fibroblastic IMR-90 cells, [3H]thymidine incorporation was stimulated by either zinc or TSP; a simultaneous treatment with zinc and TSP showed an additive effect. The present data suggest that zinc may be a unique heavy metal that potentiates the proliferation of vascular smooth muscle cells stimulated by TSP; in addition, such an interaction was observed selectively in this cell type. Since a large amount of TSP is released from alpha-granules of aggregated platelets, zinc may augment TSP activity which is involved in the physiology of vascular tissues.

Animals↗
PubMed1995

Induction of metallothionein by thrombin in cultured vascular endothelial and smooth muscle cells.

Metallothionein induction by thrombin was investigated using a culture system of vascular endothelial and smooth muscle cells. It was found that the protease induced metallothionein in endothelial cells derived from human aorta and umbilical vein as well as bovine aorta in a concentration-dependent manner. Thrombin also induced metallothionein in vascular smooth muscle cells derived from bovine aorta but not in cells derived from human, rabbit and rat aortas. In bovine aortic endothelial and smooth muscle cells, induction of metallothionein by thrombin was unaffected by the protein kinase C inhibitor staurosporine; in addition, a protein kinase C activator, phorbol 12-myristate 13-acetate, failed to induce metallothionein, suggesting that the induction by thrombin occurred through pathway(s) other than protein kinase C activation. It is suggested that metallothionein may be induced during hemostasis in the vascular tissue through protein kinase C-independent pathway(s).

Animals↗