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Biomedical subjects

R Sasaki

Publications and source records attributed to R Sasaki.

At least 19 recordsLinked to original sources
PubMed2006

Mitochondrial DNA determines androgen dependence in prostate cancer cell lines.

Prostate cancer progresses from an androgen-dependent to androgen-independent stage after androgen ablation therapy. Mitochondrial DNA plays a role in cell death and metastatic competence. Further, heteroplasmic large-deletion mitochondrial DNA is very common in prostate cancer. To investigate the role of mitochondrial DNA in androgen dependence of prostate cancers, we tested the changes of normal and deleted mitochondrial DNA in accordance with the progression of prostate cancer. We demonstrated that the androgen-independent cell line C4-2, established by inoculation of the androgen-dependent LNCaP cell line into castrated mice, has a greatly reduced amount of normal mitochondrial DNA and an accumulation of large-deletion DNA. Strikingly, the depletion of mitochondrial DNA from androgen-dependent LNCaP resulted in a loss of androgen dependence. Reconstitution of normal mitochondrial DNA to the mitochondrial DNA-depleted clone restored androgen dependence. These results indicate that mitochondrial DNA determines androgen dependence of prostate cancer cell lines. Further, mitochondrial DNA-deficient cells formed tumors in castrated athymic mice, whereas LNCaP did not. The accumulation of large deletion and depletion of mitochondrial DNA may thus play a role in the development of androgen independence, leading to progression of prostate cancers.

Androgens↗
PubMed2005

Anoxic depolarization of rat hippocampal slices is prevented by thiopental but not by propofol or isoflurane.

BACKGROUND: There is strong evidence to suggest that anoxic depolarization (AD) is an important factor in hypoxia/ischaemia-induced neural damage. Treatments that prevent the occurrence of AD may be useful in providing neuronal protection against hypoxia. The current study was designed to determine whether general anaesthetics which have been suggested to 'induce prophylaxis' against hypoxia can attenuate the incidence of AD. METHODS: The effects of anoxia (3 min) on evoked extracellularly recorded field potentials of CA1 neurons in rat hippocampal slices were assessed in the absence and presence of the i.v. general anaesthetics thiopental and propofol and the volatile anaesthetic isoflurane. RESULTS: In the absence of anaesthetics, AD occurred in 81% of the preparations tested. Thiopental (2 x 10(-4) M) significantly reduced the incidence of AD (16%, P=0.0006). In comparison, propofol (2 x 10(-4) M) and isoflurane (1.5 vol%) were ineffective (69% and 60%, respectively). Furthermore, in the presence of thiopental, the population spike amplitude recovered with and without AD (90% and 94% of pre-anoxic value, respectively) following 3 min anoxia. CONCLUSION: The prophylactic effect of thiopental against hypoxia might be induced, in part, by preventing the generation of AD.

Anesthetics, Inhalation↗
PubMed2004

Overview of mammalian zinc transporters.

In recent years, a number of mammalian zinc transporters have been identified, and candidate genes are rapidly growing. These transporters are classified into two families: ZIP (ZRT, IRT-like protein) and CDF (cation diffusion facilitator). ZIP members facilitate zinc influx into the cytosol, while CDF members facilitate its efflux from the cytosol. Molecular characterization of the transporters has brought about major advances in our understanding of their physiological functions. Zinc metabolism is regulated primarily through zinc-dependent control of transcription, translation, and intracellular trafficking of transporters. Analyses of mice whose zinc transporter genes have been genetically disrupted and of the naturally occurring mutant mice with symptoms related to abnormal zinc metabolism have provided compelling evidence that some zinc transporters play critical roles in zinc homeostasis. In this review, we review the literature of mammalian zinc transporters with emphasis on very recent findings and elicit integrative knowledge of zinc homeostasis.

Animals↗
PubMed2002

Early-onset, rapidly progressive familial tauopathy with R406W mutation.

An early-onset and rapidly progressive familial tauopathy with R406W mutation is described. The patient was a 47-year-old man who first presented with psychiatric symptoms followed by overt dementia at age 52 and died 1 year later. Postmortem study revealed tangle-associated neuronal degeneration, accentuated in the medial temporal lobe. R406W mutation was determined by sequence analysis and immunocytochemically with anti-mutant tau antibody.

Age of Onset↗
PubMed2002

Case of radiation-induced esophageal ulcer worsened after endoscopic biopsy.

Esophageal ulcer is one of the most important late complications of the esophagus treated with radiation therapy, especially with intraluminal brachytherapy. We encountered a patient with esophageal cancer treated with external radiation therapy and intraluminal brachytherapy, who developed radiation ulcer and who had severe dysphagia soon after endoscopic biopsy of the ulcer edge. A 55-year-old man was diagnosed as esophageal cancer without symptoms. He received 60 Gy/30 Fr of external radiation therapy and 12 Gy/3 Fr of intraluminal brachytherapy at a point of 5 mm in depth from the mucosa surface. He developed an asymptomatic esophageal ulcer 13 months after treatment, and endoscopic biopsy was obtained from the edge of the ulcer. Thereafter, swallowing difficulties appeared, and endoscopy revealed severe esophageal stenosis and a deep ulcer. A possibility that the biopsy contributed to worsening the ulcer can be considered. Except for cases where relapse is apparent, endoscopic biopsy is considered to be avoided.

Biopsy, Needle↗
PubMed2001

Additional gene therapy with Ad5CMV-p53 enhanced the efficacy of radiotherapy in human prostate cancer cells.

PURPOSE: The aim of this study was to investigate the efficacy of combination therapy of ionizing radiation (IR) and adenoviral p53 gene therapy and to evaluate its molecular mechanisms. METHODS AND MATERIALS: Two human prostate cancer cell lines, DU145 and PC-3 cells, containing different types of p53 gene mutations, were investigated. The recombinant adenovirus vector containing the wild-type p53 gene (Ad5CMV-p53) was used for this study. Cells were irradiated (in 0, 2, 4, and 6 Gy, 300 cGy/min) and after 12 h of irradiation, the cells were infected with various doses of Ad5CMV-p53 (0-40 multiplicity of infection [MOI]). Cytotoxicity was determined by clonogenic assay. The molecular mechanisms were evaluated by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), apoptotic cell detection, and cell cycle analysis. RESULTS: The cell growth inhibition in DU145 (p53-mutated) cells by IR was strongly enhanced by additional Ad5CMV-p53 infection in a viral dose-dependent manner. In DU145 cells, IR alone induced minimal p53 mRNA expression. However, IR combined with Ad5CMV-p53 infection stimulated significant increase in p53 mRNA expression supplemented with Bax and p21 mRNA expressions. In PC-3 (p53-null), IR induced Bax and p21 mRNA expression, while the combination effects were observed in p53, Bax, and p21 mRNA expression. Apoptotic cell deaths were rarely observed after IR alone (DU145: 3%, PC-3: 5%). However, after combination therapy, the proportion of apoptotic cells greatly increased (sevenfold in DU145 cells, and twice in PC-3 cells). G1 cell cycle arrest was observed after Ad5CMV-p53 infection and the combination in both cell lines. CONCLUSION: In this study, we demonstrated that the combination of IR and Ad5CMV-p53 gene therapy resulted in remarkable synergistic effects in human prostate cancer cells. This combination therapy could be one of the optimal treatment strategies for radioresistant prostate cancer.

Adenoviridae↗
PubMed2001

Drug-resistant human bladder-cancer cells are more sensitive to adenovirus-mediated wild-type p53 gene therapy compared to drug-sensitive cells.

We investigated the therapeutic potential and molecular mechanism of adenovirus-mediated wt p53 gene therapy for drug-resistant human bladder cancers. KK47, a human bladder-cancer cell line, along with the drug-resistant sublines KK47/DDP10, KK47/DDP20 (cisplatin-resistant) and KK47/ADM (doxorubicin-resistant) were used for the experiments. All 4 KK47 cell lines had genetically normal p53 genes. Using an in vitro cytotoxicity assay, the drug-resistant cell lines were more sensitive to Ad-CMV-p53 cell killing than the KK47 parental cell line. Ad-CMV-p53 induced higher levels of p53 protein and mRNA in the drug-resistant cell lines than in the parental cell line and, consequently, higher levels of p21 and Bax mRNA, which resulted in higher percentages of G(1) cell-cycle arrest and apoptosis. The higher efficiencies of adenoviral gene transfer in the drug-resistant cell lines were confirmed by X-gal staining after infection with Ad-CMV-beta-gal. In conclusion, adenovirus-mediated wt p53 gene therapy was more effective in the drug-resistant bladder-cancer cell lines than in the drug-sensitive bladder-cancer cell line.

Adenoviridae↗
PubMed2001

BAG-1M, an isoform of Bcl-2-interacting protein BAG-1, enhances gene expression driven by CMV promoter.

BAG-1M, one of the isoforms of BAG-1, was reported to bind to DNA and stimulate general transcription when cells were stressed by heat shock (Zeiner, M., et al., Proc. Natl. Acad. Sci. USA 96, 10194-10199, 1999). Here we show that BAG-1M binds and enhances transcriptional activity of Cytomegalovirus (CMV) early gene promoter under unstressed conditions. This activity is unique to BAG-1M in that other isoforms, BAG-1S and BAG-1L, are much weaker in this activity, although all of the isoforms share common ubiquitin-like domain and BAG domain interacting with Hsp70/Hsc70. Deletion analysis of BAG-1M showed that C-terminal BAG domain is necessary to enhance the CMV promoter activity, suggesting that interaction with Hsp70/Hsc70 proteins may mediate this function. Another mutation in N-terminus, BAG-1M K(2-4)A, lost DNA binding capacity and majority of the promoter-enhancing activity. Our study demonstrates that both N-terminal DNA binding site and C-terminal Hsp70/Hsc70 binding site of BAG-1M play an important role in enhancing the CMV promoter activity.

Carrier Proteins↗
PubMed2001

Involvement of PLAGL2 in activation of iron deficient- and hypoxia-induced gene expression in mouse cell lines.

We searched iron-deficient inducible cDNA, using subtraction cloning and mRNA from desferrioxamine-treated mouse macrophage Raw264.7 cells. We identified a pleomorphic adenoma gene like 2 (PLAGL2), one of PLAG superfamily proteins exhibiting antiproliferative properties on tumor cells. Mouse PLAGL2 consists of 496 amino acids with seven C2H2 zinc-fingers. PLAGL2 mRNA was induced in RAW264.7 cells, mouse erythroleukemia cells and Balb/c 3T3 cells when they were treated with desferrioxamine. Hypoxia also increased PLAGL2 mRNA. Expression of PLAGL2 in COS-7 cells led to nuclear localization. PLAGL2 had potential binding ability to GC-rich oligonucleotide and activated transcription of a gene with the binding sequence in transient reporter assay, a finding consistent with a case seen in a PLAGL2 homolog, ZAC-1. Transient co-transfection of PLAGL2 or ZAC1 cDNA and a reporter containing a lactate dehydrogenase A (LDHA) promoter carrying the hypoxia inducible factor-1 responsive element led to an increase in the basal transcription in Balb/c 3T3 and HepG2 cells. Activation in transcription from the LDHA promoter increased by desferrioxamine treatment or hypoxia was further enhanced when PLAGL2 was expressed. We propose that PLAGL2 is involved in the cell cycle arrest and apoptosis of tumor cells by regulating iron depletion- or hypoxia-inducible gene expression.

Amino Acid Sequence↗
PubMed2001

Clinical significance of serum pulmonary surfactant proteins a and d for the early detection of radiation pneumonitis.

PURPOSE: Radiation pneumonitis (RP) is one of the most serious complications for patients who receive thoracic irradiation. To avoid this, early diagnosis of radiation pneumonitis is extremely important. The purpose of the present study is to investigate whether serum pulmonary surfactant proteins A and D (SP-A and SP-D, respectively) could be useful markers for RP. METHODS AND MATERIALS: Eighty-six patients (lung cancer: 42 [primary: 39, metastatic: 3], breast cancer: 23, esophageal cancer: 21) who underwent radiation therapy were prospectively studied. Radiation doses ranged from 30-76 Gy (median, 58 Gy). Serum SP-A and SP-D levels were evaluated sequentially by a sandwich enzyme-linked immunosorbent assay (ELISA) method before, during, and throughout the follow-up period until the development of symptomatic RP or until one year after completion of radiotherapy. Specificity of the ELISA results was confirmed by Western blot analysis. Patients symptomatic for RP were graded according to the Common Toxicity Criteria. RESULTS: RP occurred in 19 patients. Serum SP-D levels of patients with RP were sequentially higher than those in patients without RP. In the monitoring, serum SP-D levels at 50-60 Gy showed greater sensitivity and positive predictive values for RP detection (74% and 68%, respectively) than SP-A (26% and 21%, respectively). Western blot analysis showed that the development of RP was due to overproduction, but not proteolysis of surfactant proteins. CONCLUSION: We confirm that serum SP-A and SP-D monitoring is a practical and useful diagnostic method for the early detection of RP.

Aged↗
PubMed2001

Inhibition of erythropoietin signalling destroys xenografts of ovarian and uterine cancers in nude mice.

We have recently shown that malignant tumours from the ovary and uterus expressed erythropoietin (Epo) and its receptor (EpoR), and that deprivation of Epo signal in tumour blocks induced death of malignant cells and capillary endothelial cells in vitro (Yasuda et al, submitted). These in vitro results prompted us to examine the effect of Epo-signal withdrawal on tumours in vivo. RT-PCR analysis demonstrated the expression of mRNAs for Epo and EpoR in the transplants of uterine and ovarian tumours in nude mice. Then we injected locally anti-Epo antibody or soluble form of EpoR into the transplants. At 12 h, 1, 7 or 14 days after the injection, all transplants were resected and examined macro- and microscopically. Tumour size was reduced in Epo signal-deprived transplants. Immunohistochemical examinations revealed destruction of Epo-responding malignant and capillary endothelial cells through apoptotic death. The degree of tumour regression correlated well with the dose and frequency of the injections. Control xenografts with saline injection or needle insertion showed well-developed tumour masses. This Epo response pathway will have profound implications for our understanding of the development and progression of malignant tumours and for the use of Epo-signal deprivation as an effective therapy.

Animals↗
PubMed2001

A novel CLCN1 mutation: P480T in a Japanese family with Thomsen's myotonia congenita.

At least 50 disease-causing mutations in the skeletal muscle voltage-gated chloride channel gene (CLCN1), almost all of which originate from Caucasian families, have been identified. We investigated a Japanese family with Thomsen's myotonia congenita that included 16 affected individuals (8 men and 8 women) through five generations. Polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) screening of 11 members showed an aberrant conformer in exon 13 of CLCN1 complementary DNA (cDNA) in 8 affected and 1 unaffected members. By sequence analysis, we identified a C-to-A transition at nucleotide position 1438, resulting in a substitution of proline for threonine at amino acid position 480 (P480T), the same position of the original mutation (P480L) in Thomsen's disease. The P480T mutation was novel and absent in 100 normal controls. Seven of the 8 affected individuals were heterozygous; another, from affected parents, was homozygous. Clinically, myotonia in the homozygous patient was more severe than that in heterozygous patients, probably due to the gene dosage effect. On a long-train nerve-stimulation test at a rate of 3 Hz, M-wave responses in the homozygous patient showed marked decrement followed by recovery. In contrast, the heterozygous patients showed just a slight decrement or no changes, and none of 2 patients with myotonic muscular dystrophy or 2 normal controls revealed any decrement. Thus, the long-train nerve-stimulation test at a low stimulus frequency may be a useful tool to assess the disease-severity/genotype relationship in myotonia congenita.

Adult↗
PubMed2001

Reciprocal regulation of tissue-type and urokinase-type plasminogen activators in the differentiation of murine preadipocyte line 3T3-L1 and the hormonal regulation of fibrinolytic factors in the mature adipocytes.

Adipose tissue expresses a variety of genes including tumor necrosis factor alpha and type-1 plasminogen activator inhibitor (PAI-1); and these factors, produced by adipocytes, may be associated with the risk of coronary events in obesity. In this study, we characterized the production of fibrinolytic factors including tissue-type plasminogen activator (tPA), urokinase-type PA (uPA), and PAI-1 in the differentiation of preadipocytes, and examined the hormonal regulation of these fibrinolytic factors in mature adipocytes. Mouse 3T3-L1 preadipocytes were employed as a model of adipocytes. Adipocyte differentiation was induced by insulin, dexamethasone, and 3-isobutyl-1-methyl xanthine (IBMX). alpha-Glycerophosphate dehydrogenase (GPDH) activity and glucose transporter 4 (GLUT4) mRNA, indices for adipocyte maturation, were induced on Day 4, and gradually increased. GPDH activity reached its maximum level on Day 14. The level of tPA, a major PA in preadipocytes, dramatically decreased with differentiation. On the other hand, that of uPA reciprocally increased. PAI-1 production was also dramatically induced concomitant with differentiation. In mature adipocytes, uPA production was dominant (25 microg/ml/24 h vs. 0.8 microg/ml/24 h for tPA). Total PA activity in the mature adipocytes was reduced by insulin or dexamethasone, but not by glucagon. Insulin, IBMX, and dexamethasone significantly decreased both uPA and tPA production, and increased PAI-1 production. Glucagon had no effect on the production of these fibrinolytic factors. Our results reveal that uPA is one of the markers for the differentiation of 3T3-L1 cells and that insulin, IBMX, and dexamethasone are potent regulators of the fibrinolytic activity in differentiated 3T3-L1 cells, reciprocally affecting PA and PAI-1 levels in them.

1-Methyl-3-isobutylxanthine↗
PubMed2001

Expression of human brain carboxypeptidase B, a possible cleaving enzyme for beta-amyloid precursor protein, in peripheral fluids.

Human brain carboxypeptidase B (HBCPB) is a novel brain protease that processes native brain beta-amyloid precursor protein (APP) in vitro. Immunoblot analysis of human serum and cerebrospinal fluid (CSF) using anti C14-module antibody, which recognizes the C-terminal peptide unique to HBCPB, detected the 30 and 40 kDa immunoreactive bands. Analysis of HBCPB prepared from both serum and CSF demonstrated proteolytic activities for brain APP. Protease inhibitor spectrum analysis also supports that these bands correspond to the mature form and and prepro form of HBCPB, respectively. As is the case in brain parenchyma, the prepro-form is dominant in CSF. In serum, however, the majority of HBCPB exists in the mature form, possibly due to an abundant trypsin-like proteolytic activity in serum. HBCPB expressed in serum and CSF, therefore, may have a significance as a peripheral marker of the brain protease, which participates in APP processing in human brain.

Alzheimer Disease↗
PubMed2001

Prognostic significance of lymph node involvement in middle and distal bile duct cancer.

BACKGROUND: Although lymph node involvement is considered an important prognostic factor, a detailed analysis has not been conducted in middle (Bm) and distal (Bi) bile duct cancer. METHODS: The histopathology of resections taken from 59 patients with Bm and Bi disease (Bm, 33 patients; Bi, 26 patients) was examined. The prevalence of lymph node involvement and its relationship to recurrence and prognosis were investigated. Survival rates were investigated according to the number of metastatic lymph nodes found, the TNM nodal stages, and the nodal stage classifications of The General Rules of the Japanese Society of Biliary Surgery. RESULTS: The frequency of nodal involvement in Bm and Bi was 45.5% and 30.8%, respectively. A significant correlation existed between a patient's prognosis and his TNM nodal stage, Japanese Society of Biliary Surgery nodal stage, and the number of metastatic lymph nodes found (P <.0001, respectively). Among 8 sites of postoperative recurrence, metastasis occurred most frequently in the liver (16/23). Patients with nodal involvement had a significantly higher rate of liver metastasis (10/23) than those without it (6/36) (P =.024). CONCLUSIONS: The number of metastatic lymph nodes found in patients with Bm or Bi cancer, and the nodal stage of their nodes, are significant prognostic indicators. Patients with nodal involvement are at high risk for liver metastasis in Bm and Bi disease.

Adult↗
PubMed2001

Pilot study of local radiotherapy for portal vein tumor thrombus in patients with unresectable hepatocellular carcinoma.

BACKGROUND: Patients suffering from hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT) generally have a poor prognosis. We therefore conducted a prospective pilot trial of combined transcatheter arterial chemoembolization (TACE) and local radiotherapy (RT) for PVTT in unresectable HCC. The aim of the study was to investigate the efficacy and toxicity of this preliminary trial regime and to explore RT guidelines for cirrhosis. METHODS: Eight patients with unresectable HCC accompanied by first branch PVTT were entered into the study from February 1998 to December 1999. TACE was performed using Lipiodol, epirubicin hydrochloride and mytomycin followed by gelatin sponge cubes. RT was started 10-14 days following TACE. A total delivered dose of 60 Gy was given as daily 2 Gy fractions, with the clinical target volume defined as PVTT only. We observed a relationship between deterioration of liver function and the percent volume of the total liver receiving a dose exceeding 30 Gy (V30). RESULTS: An objective response was observed in three of the eight patients. However, on follow-up angiograms the protrusion of PVTT into the main portal trunk was decreased in all cases. Deterioration of liver function was observed in all patients with V30 >40%. CONCLUSION: It is possible that this combined therapy prevents PVTT from spreading to the main trunk and that indicates a further benefit of TACE. Our results indicate that V30 constitutes a predictive test for the development of liver failure. More detailed evaluations of liver function and determination of the safe irradiation volume are necessary.

Aged↗