Biomedical subjects

Y Takemura

Publications and source records attributed to Y Takemura.

At least 19 recordsLinked to original sources

PubMed1999

Microsatellite instability and clonal heterogeneity of MDR1 messenger RNA expression in trimetrexate-resistant human leukemia MOLT-3 cells developed in thymidine.

Various gene alterations are involved in the drug resistance of leukemia cells. To understand the mechanism that underlies the emergence of cells with such gene alterations in human leukemia, we performed clonal analysis of the gene expression of mutant dihydrofolate reductase (DHFR) and mdr1 in trimetrexate-resistant human leukemia MOLT-3 cells. Trimetrexate-resistant (70- and 60-fold) sublines were developed in the presence or absence of an exogenous supply of thymidine (MOLT-3/TMQ70/Th+, MOLT-3/TMQ60/Th-, respectively). Ten clonal lines were isolated by methyl cellulose cloning from each of the 2 trimetrexate-resistant MOLT-3 sublines. All the clonal lines from the 2 sublines expressed mutated DHFR mRNA, with a base change (T --> C) at the second position of codon 31, as well as the wild-type mRNA, in accordance with cross-resistance to methotrexate. On the other hand, mdr1 mRNA expression was demonstrated by reverse-transcription polymerase chain reaction only in clonal lines from MOLT-3/TMQ70/Th+ cells. mdr1 mRNA expression in clonal lines from MOLT-3/TMQ70/Th+ cells and subclonal lines subsequently obtained from the 3 clonal lines with different mdr1 mRNA expression levels was heterogeneous, and its high expression levels were correlated with acquisition of the multidrug resistance (MDR) phenotype. Polymerase chain reaction-based assay for separate microsatellites, mfd27 and mfd41, demonstrated genomic instability among clonal and subclonal lines of MOLT-3. The clonal analysis of polymorphic microsatellites also suggested that emergence of MDR in trimetrexate-resistant MOLT-3 cells in thymidine was not only heterogeneous but also progressively expanding among clones. Genomic instability may play a role in the establishment and clonal evolution of drug resistance in leukemia cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Retrovirus-mediated transfer of anti-MDR1 hammerhead ribozymes into multidrug-resistant human leukemia cells: screening for effective target sites.

One of the underlying mechanisms of multidrug resistance (MDR) is cellular over-production of P-glycoprotein (P-gp), which acts as a drug efflux pump. P-gp is encoded by a small group of related genes termed MDR; only MDR1 is known to confer drug resistance. To overcome P-gp-mediated drug resistance, we have developed two anti-MDR1 hammerhead ribozymes driven by the beta-actin promoter. Upon transduction of the ribozymes into MDR cells, vincristine resistance was decreased. These two ribozymes were constructed, which showed different cleavage activities. In this study, to determine suitable target sites for the anti-MDR1 ribozyme, the exon 1b-intron 1 boundary, the translation-initiation site, the intron 1-exon 2 boundary and the exon 2-intron 2 boundary, codons 179 and 196 of the MDR1 gene were selected as candidates. To improve the ribozyme activity, a retroviral vector containing RNA polymerase III promoter was used. Stable retrovirus producer cells were generated by transfecting the retroviral vector plasmids carrying the ribozyme into the packaging cell line. Retroviral vector transduction of human leukemia cell lines expressing MDR1 was accomplished by co-culturing these with virus producer cells. Stably transduced cells were selected by G418 and pooled to determine the efficacy of each ribozyme. These ribozyme-transduced cells became vincristine-sensitive concomitant with the decreases in MDR1 expression, P-gp amount and drug efflux pump function. Among the ribozymes tested, the anti-MDR1 ribozyme against the translation-initiation site exhibited the strongest efficacy. This retrovirus-mediated transfer of anti-MDR1 ribozyme may be applicable to the treatment of MDR cells as a specific means to reverse resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Inhibitory effect of Epstein-Barr virus activation by Citrus fruits, a cancer chemopreventor.

To search useful compounds in Citrus fruit for cancer chemoprevention, we carried out a primary screening of extracts of fruit peels and seeds from 78 species of the genus Citrus and those from two Fortunella and one Poncirus species, which were closely related to the genus Citrus. These Citrus extracts inhibited the Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) as a useful screening method for anti-tumor promoters. Our results indicated that Citrus containing substances may be inhibit susceptibility factors involved in the events leading to the development of cancer.

Animals↗

PubMed1999

The protective effect of good physical fitness when young on the risk of impaired glucose tolerance when old.

BACKGROUND: The role of physical activity or fitness on preventing impaired glucose tolerance (IGT) has not been widely investigated. The present case-control study examined the relationship between the occurrence of IGT in men in their 50s and the level of their physical fitness while in their 30s. METHODS: The subjects consisted of 38 male Japan Self-Defense Forces officials in their 50s who had IGT, as diagnosed by the 75-g oral glucose tolerance test, and 60 control individuals. Nine diabetics were included in the IGT cases. As an indicator of physical fitness between the ages of 30 and 39 years, we selected the best time recorded for each individual during that decade of life for the 1,500-m physical fitness test run. We calculated the odds ratio for IGT in relation to selected risk factors (including physical fitness), and a logistic regression analysis was used to adjust for possible confounding variables. RESULTS: The odds ratio (95% confidence interval, P value) for IGT with physical fitness in their 30s was 0.25 (0.11-0.58, P < 0.05). With adjustment for a parental history of diabetes and body mass index in both their 30s and their 50s, the odds ratio was 0.31 (0.11-0.86, P < 0.05). CONCLUSIONS: We concluded that the occurrence of IGT, including diabetes, in men in their 50s can be reduced by maintaining a high level of physical fitness while in their 30s.

Adult↗

PubMed1999

Acridones as inducers of HL-60 cell differentiation.

Fifteen acridone alkaloids were examined for their activity of induction of human promyelocytic leukemia cell (HL-60) differentiation. HL-60 cells were differentiated into mature monocyte/macrophage by atalaphyllidine (9), atalaphyllinine (12), and des-N-methylnoracronycine (13). The activities of NBT reduction, nonspecific esterase, and phagocytosis, were induced by 2.5 microM of 9, 12, and 13. After a 4-day treatment, 9, 12, and 13 at 10 microM inhibited clonal proliferation of HL-60 cells by 28, 96, and 63%, respectively. The structure-activity relationship established from the results revealed that hydroxyl group at C-1 and prenyl group at C-2 had an important role.

Acridines↗

PubMed1999

The antiproliferative effect of acridone alkaloids on several cancer cell lines.

Fifteen acridone alkaloids were examined for their antiproliferative activity toward monolayers and suspension of several types of cancer and normal human cell lines. As a result, atalaphyllidine (9), 5-hydroxy-N-methylseverifoline (11), atalaphyllinine (12), and des-N-methylnoracronycine (13) showed potent antiproliferative activity against tumor cell lines, whereas they have weak cytotoxicity on normal human cell lines. The structure-activity relationship established from the results revealed that a secondary amine, hydroxyl groups at C-1 and C-5, and a prenyl group at C-2 played an important role for antiproliferative activities of the tetracyclic acridones.

Acridines↗

PubMed1999

Relation between the serum level of C-peptide and risk factors for coronary heart disease and diabetic microangiopathy in patients with type-2 diabetes mellitus.

Syndrome X is used to describe a constellation of factors that lead to coronary heart disease (CHD): hypertension, hyperinsulinemia, impaired glucose tolerance, and an abnormality in lipid metabolism. We investigated the relationship between serum levels of C-peptide immunoreactivity (CPR) and diabetic complications in 256 patients with type-2 diabetes mellitus. The serum level of CPR was measured by radioimmunoassay (RIA). Diabetic patients were divided into 3 groups according to the serum level of CPR as follows: low CPR (n = 19, <0.7 ng/ml), normal CPR (n = 174, 0.7 to 2.2 ng/ml) and high CPR (n = 63, >2.2 ng/ml). The body mass index (BMI) and the serum level of triglycerides were significantly higher in the high CPR group (P < 0.05, respectively) compared with normal CPR group. The prevalence of hypertension was significantly higher in the high CPR group than in the other 2 groups (low CPR: 16%, normal CPR: 28%, high CPR: 38%). The frequency of the number of patients receiving insulin therapy was greater in the low CPR group than in the other 2 groups, (low CPR: 58%, normal CPR: 15%, high CPR: 11%). The serum CPR level was significantly lower in patients with than without proliferative retinopathy or macroalbuminuria. Our conclusion is that the present data suggest that an increased serum level of CPR is associated with obesity, elevated serum triglycerides, and hypertension in patients with type-2 diabetes mellitus. A low CPR level leading to hyperglycemia is associated with the progression of diabetic microangiopathies, such as retinopathy and nephropathy.

Albuminuria↗

PubMed1999

Variable expression of the folylpolyglutamate synthetase gene at the level of mRNA transcription in human leukemia cell lines sensitive, or made resistant, to various antifolate drugs.

We investigated the expression of the folylpolyglutamate synthetase (FPGS) gene at the mRNA level in MOLT-3 and K562 human leukemia cell lines sensitive, or made resistant, to methotrexate (MTX) and/or trimetrexate (TMQ), or raltitrexed (ZD1694). Northern blot analysis demonstrated approximately 3-fold higher FPGS mRNA expression in K562 cells than that in MOLT-3 cells, being consistent with graded polyglutamation capacities of these cell lines. A slight increase in the expression of the FPGS gene was observed in the TMQ-resistant MOLT-3 cells (MOLT-3/TMQ800); moreover, sequential development of MTX resistance in the TMQ-resistant cells (MOLT-3/TMQ800-MTX10,000) resulted in a further enhancement of FPGS mRNA expression despite of decreased polyglutamation capacity in this subline. Another MTX-resistant subline with impaired reduced folate carrier (MOLT-3/MTX10,000) also showed overexpression of FPGS mRNA. Conversely, both raltitrexed-resistant sublines (MOLT-3/ZD1694 x C and K562/ZD1694 x C) displayed a moderately decreased expression of FPGS mRNA. These findings did not correspond to the virtual absence of ZD1694 polyglutamates inside the former cells nor to possibly intact polyglutamation capacity in the latter cells. These results indicate that FPGS mRNA expression may predict cellular ability to produce polyglutamate metabolites of antifolate drugs in the sensitive cells, but does not necessarily reflect FPGS function at the enzyme level in the antifolate-resistant tumor cells.

Drug Resistance, Neoplasm↗

PubMed1999

Does psychological stress improve physical performance?

The purpose of this study is to determine whether psychological stress enhances physical performance and how personality traits affect it. The annual physical test was chosen as the psychological stressor. Ninety three students ran 50 meters as part of the test and one week after that as a control. The pulse rate and time were measured and pulse rate was used as an indicator of psychological stress. All students took the anxiety-trait scale test of the State-Trait Anxiety Inventory. The pulse rate was higher and the time record was better in the annual physical test compared with that of control. When we categorized the subjects by the anxiety-trait scale test, only the high anxiety-trait students could run faster when faced with higher stress. In conclusion, psychological stress can enhance the physical performance of certain students. It is possible that psychological stress and personality traits interact and both of them affect physical performance.

Adolescent↗

PubMed1999

The effects of a fixed-fee reimbursement system introduced by the Federal Government on laboratory testing in the United States.

Rapid growth of health care expenditures during the 1970s in the United States led to implementation of a prospective payment system (PPS) based on diagnosis-related groups (DRG) for Medicare inpatient reimbursement in 1983. With the introduction of DRG/PPS, hospitals encouraged earlier discharges and discouraged admission of patients who may require expensive services. Patient care has moved into more outpatient and non-hospital settings which have been less regulated and paid on a cost-reimbursement basis. The change of reimbursement system has converted hospital laboratories from "profit center" under the fee-for-service reimbursement practice to possible "cost center" at least for inpatient laboratory services with the advent of DRG/PPS. Hospitals have reduced laboratory operating expenses by constraining laboratory growth and development. Laboratory testing in non-hospital settings such as physicians' office laboratories, which were exempt from license and quality control by governmental regulations, has increased exponentially since implementation of DRG/PPS. To improve the quality of laboratory testing in such unregulated laboratories, the federal government has promulgated the Clinical Laboratory Improvement Amendments of 1988 (CLIA '88), requiring on-site survey and license under CLIA '88 for all laboratories in the United States regardless of the size, complexity, or location of laboratory. Implementation of DRG/PPS resulted in a temporary success in reducing Medicare Part A budget growth, but had only a small impact to slow the actual growth of total national health care expenditures or laboratory-related expenditures. Nevertheless, the change of reimbursement practice has created a large incentive to reduce unnecessary resource utilization, and cost-effective laboratory testing has become an essential concept during the DRG/PPS era.

Clinical Laboratory Techniques↗

PubMed1999

[CT diagnosis of hyperdense intracranial neoplasms: review of the literature].

In contrast to typical astrocytic tumors that show hypodense areas on computed tomographic images, some intracranial tumors show hyperdense areas on CT images. The major reasons for hyperdensity on CT images are hypercellular lesions, intratumoral calcification, and intratumoral hemorrhage. Malignant lymphomas, germinomas, and medulloblastomas show homogeneous hyperdensity on CT images because of their hypercellularity. Tumorous lesions such as subependymal giant cell astrocytomas, oligodendrogliomas, ependymomas, central neurocytomas, craniopharyngiomas, and meningiomas often present with hyperdense calcified lesions on CT images. Intratumoral hemorrhage also causes hyperdensity on CT images, and is often associated with metastatic brain tumors, glioblastomas, pituitary adenomas, and rarely with any of the other intracranial tumors. Although magnetic resonance imaging is now the major diagnostic tool for diseases of the central nervous system, the first imaging studies for patients with neurologic symptoms are still CT scans. Hyperdense areas on CT images are a clue to making an accurate diagnosis of intracranial neoplasms.

Adult↗

PubMed1999

[Anti-thyroid peroxidase antibody].

Anti-thyroid peroxidase antibody(TPOAb) in patients with autoimmune thyroid diseases was identified with anti-microsomal antibody. Highly sensitive assays of TPOAb using radioimmunoassays and enzyme immunoassays have been developed following a hemagglutination assay technique. TPOAb is present in the serum of almost all patients with Hashimoto's thyroiditis, in more than 70% of those with Graves' disease, and, to a variable degree, in patients with nonthyroid autoimmune diseases and some normal subjects. There is a good correlation between the degree of lymphocytic infiltration of the thyroid gland and the titer of TPOAb. Postpartum thyroiditis, usually a transient disorder, occurs with high frequency in women who have TPOAb. TPOAb, in addition to anti-thyroglobulin antibody, was a clinically useful marker for defining autoimmune thyroid diseases and for detecting an underlying autoimmune process in the thyroid, however, its biological importance remains to be clarified at the present time.

Autoantibodies↗

PubMed1999

Common diagnostic test panels for clinical evaluation of new primary care outpatients in Japan: a cost-effectiveness evaluation.

BACKGROUND: The Japan Society of Clinical Pathology (JSCP) has developed a guideline for common diagnostic test utilization in new primary care outpatients. To determine the scientific and economic validity of the JSCP panel testing system, we analyzed cost-effectiveness parameters of test panels advocated. METHODS: The "Essential Laboratory Tests" panel (2) [ELT(2) panel], a package of common diagnostic tests added to the ELT(1) baseline health-status screening panel, was applied to 540 new outpatients who visited the Comprehensive Medicine Clinics in an academic medical center during 1991 to 1997. A "useful result" (UR) of testing was defined as a finding that contributed to a change in a physician's diagnosis- or decision-making, relating to a "tentative initial diagnosis" (TID) obtained from history and physical examination alone. RESULTS: Clinical usefulness was demonstrated in 259 patients with ELT(2), in whom 398 URs were generated. Clinical effectiveness (UR/TID) ranged from 1.65 (hematological) to 0.088 (neurological disease), with a cost disparity from yen1251 ( approximately $10) to yen23 037 ( approximately $200) per UR. A total of 1137 tests generated URs. We further assessed the clinical effectiveness and economic efficiency (cost/UR) of ELT(1) and restructured panels. Use of the ELT(1) alone generated 244 URs in 167 patients. The poor efficiency of the ELT(1) panel was markedly improved with the addition of certain ELT(2)-specific tests in liver/pancreatobiliary, metabolic/endocrine, and cardiovascular disease groups. CONCLUSIONS: A wide disparity in the utility of ELT panels in different patient groups does not support the JSCP recommendation of their routine use for new outpatients. Selective test combinations should be used in selected patient groups.

Adolescent↗

PubMed1998

Vincristine saturation of cellular binding sites and its cytotoxic activity in human lymphoblastic leukemia cells: mechanism of inoculum effect.

Vincristine (VCR) is an active agent in the treatment of acute lymphoblastic leukemia (ALL). We evaluated the relationship between the cytotoxic activity of VCR and the degree of VCR saturation of cellular drug binding sites, using the MOLT-3 ALL cell line. When MOLT-3 cells at a density of 1 x 10(6) or 1 x 10(8) cells/mL of pH-controlled medium were exposed to VCR for 1 hr, its cytotoxic activity on cells at high density was 10-fold less than on cells at low density (inoculum effect). The number of VCR binding sites measured by Scatchard analysis was 9.25 x 10(6)/cell. At high cell density, the saturation of VCR binding sites was one log order less than that at low density. Irrespective of cell density, curves of cell-kill versus the degree of VCR saturation of the cellular binding sites overlapped each other. Minimal cytotoxic activity was observed at 0.3% VCR saturation, and nearly maximal cytotoxic activity occurred at about 25% saturation, with the Ic50 at about 4% saturation. These data show that the VCR-induced cell-kill effect is dependent on the degree of saturation of VCR binding sites rather than on the extracellular VCR concentration. The lesser cell-kill on cells at high density can be explained by the lack of drug molecules to sufficiently saturate cellular binding sites. This phenomenon may be responsible, at least in part, for the poor chemotherapeutic outcome of ALL patients with high leukocyte counts at presentation.

Antineoplastic Agents, Phytogenic↗

PubMed1998

Variable expression of RFC1 in human leukemia cell lines resistant to antifolates.

The resistance to folate-based antifolates is associated with impaired function of the reduced folate carrier (RFC), one of the major routes of folate transport into cancer cells. To clarify the importance of RFC functions in the antifolate resistance, we have examined the expression of RFC1 and its phenotype as a folate transporter in human leukemia cell lines resistant to various antifolates. MOLT-3 cells resistant to ZD9331 (a thymidylate synthase (TS) inhibitor that utilizes the RFC for cell entry) (MOLT-3/ZD9331) showed decreased expression of RFC1 concomitant with diminished cellular uptake of [3H]methotrexate (MTX). K562 cells resistant to raltitrexed (ZD1694, another TS inhibitor that utilizes the RFC for cell entry) (K562/ ZD1694 x C) scarcely expressed RFC1, which is in accordance with the impaired uptake of folate analogs and the high degree of resistance to ZD1694 and MTX. On the other hand, no apparent decrease of RFCI1 expression was found in transport-deficient MTX-resistant MOLT-3 cells (MOLT-3/MTX10000) though its phenotype showed defective transport of MTX or ZD1694. In these cell lines with impaired RFC function, [3H]leucovorin (LV) uptake was only moderately decreased as compared to [3H]MTX or [3H]ZD1694 uptake. These cells grew with a minimal retardation in folate-free medium supplemented with 10 nM LV, suggesting that these cell lines with impaired RFC function had enough folate transporters to transport LV. In contrast to downregulation of RFC, the much greater uptake of [3H]MTX was observed in the MOLT-3/trimetrexate (TMQ)800-MTX10000 in parallel with increased RFC1 expression. These cell lines with the altered expression of RFC1 may serve as models useful for investigating the regulation of RFC1 expression and for understanding the molecular mechanism(s) behind the transport-mediated antifolate resistance.

Antimetabolites, Antineoplastic↗

PubMed1998

Molecular characterization of human acute leukemia cell line resistant to ZD9331, a non-polyglutamatable thymidylate synthase inhibitor.

ZD9331 is a non-polyglutamatable, potent quinazoline antifolate inhibitor of thymidylate synthase (TS). In an effort to clarify the exact mechanism of resistance to this novel TS inhibitor, we examined the molecular alterations in its target enzyme TS, the transport protein (reduced folate carrier, RFC), and folylpolyglutamate synthetase (FPGS) in a human acute lymphoblastic leukemia cell line, MOLT-3, made resistant to ZD9331. A 310-fold resistant subline was established after 6 months exposure to the drug at concentrations up to 7 microM, and was designated MOLT-3/ ZD9331. MOLT-3/ZD9331 showed crossresistance to CB3717 (4.8-fold), raltitrexed (63-fold) and methotrexate (MTX) (120-fold), but retained sensitivity to trimetrexate (0.88-fold). The resistant cells demonstrated impaired initial cellular uptake and low accumulation of [3H]MTX in accordance with a decreased expression of RFC1, suggesting the downregulation of RFC. However, Southern blot analysis demonstrated no change in gene copy number nor gross rearrangement of RFC1 in the resistant cells. In addition, MOLT-3/ZD9331 showed amplification of the TS gene with a concomitantly increased level in the gene expression. In contrast, the expression of FPGS did not alter. These results demonstrate that continuous exposure of the cells to ZD9331 leads not only to a decreased expression of RFC1 but also to TS gene amplification and overexpression. The resistant mechanisms are likely to be regulated both at a genetic and a transcriptional level for different resistance phenotypes in the ZD9331-resistant MOLT-3 cells.

Acute Disease↗

PubMed1998

Mechanisms of elevation of serum and urinary concentrations of soluble thrombomodulin in diabetic patients: possible application as a marker for vascular endothelial injury.

Serum and urinary levels of soluble thrombomodulin (TM) were measured in 71 patients with non-insulin-dependent diabetes mellitus (NIDDM) and 132 age-matched control subjects to elucidate the mechanisms involved in increased TM levels. We compared the TM level with urinary albumin excretion (UAE), creatinine (Cr) clearance, and indices of renal tubular damage such as urinary beta2-microglobulin. Serum TM was significantly higher in diabetic patients versus control subjects (P < .001) regardless of whether the patients had diabetic nephropathy. Urinary TM levels were also higher in diabetic patients than in control subjects (P < .001). Serum TM in diabetic patients was correlated positively with serum Cr and UAE and inversely with the Cr clearance rate (P < .001, respectively). The urinary level of TM in diabetic patients was significantly correlated with 24-hour glucose excretion and the serum level of 1,5-anhydroglucitol (1,5-AG) (P < .001). However, no correlations were found between urinary TM levels and renal function in diabetic patients. There was also no correlation between serum and urinary levels of TM in the patients. These results suggest that although the serum TM level is influenced by an impairment of the renal clearance of TM, this parameter may be a useful marker for vascular endothelial injury in diabetic patients. On the other hand, since the elevated urinary level of TM in the patients paralleled their urinary excretion of glucose, urinary TM levels do not correlate with vascular endothelial injury in diabetic patients.

Adult↗

PubMed1998

Power spectral analysis of variations in heart rate in patients with hyperthyroidism or hypothyroidism.

Power spectral analysis (PSA) of the variation in heart rate is useful in determining the relative activity of the sympathetic and parasympathetic nerves. In this study, PSA was used to investigate the relationship between abnormalities in autonomic nerve function and the presence of thyroid disorders in patients with autoimmune thyroid diseases. The low frequency (LF) or high frequency (HF) components of R-R variations were determined by PSA. The coefficient of variation of the R-R time intervals (CV(R-R)) was positively correlated with HF in healthy subjects. In untreated hyperthyroid patients with Graves' disease, the CV(R-R) and HF values were significantly lower than in healthy controls. Moreover, the LF/HF ratio in patients with untreated Graves' disease was significantly higher, and the LF/HF ratio in hypothyroid patients with Hashimoto's thyroiditis was significantly lower than in healthy controls. A negative correlation was observed between serum levels of free thyroid hormones (FT4 and FT3) and HF in Graves' disease patients. In some hyperthyroid patients, antithyroid drug therapy or beta-blocker administration gradually restored reduced HF values. Present results suggest that relative vagal nerve activity is reduced in hyperthyroid patients and that this reduction is reversible according to the decrease in serum levels of thyroid hormones.

Adrenergic beta-Antagonists↗