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Biomedical subjects

K Tamura

Publications and source records attributed to K Tamura.

At least 199 records · Page 11Linked to original sources
PubMed2000

Usefulness of PET with 11C-methionine for the detection of hilar and mediastinal lymph node metastasis in lung cancer.

UNLABELLED: We retrospectively evaluated the usefulness of PET with 11C-methionine (methionine PET) for the diagnosis of lymph node metastases in patients with lung cancer. METHODS: Methionine PET and CT were performed before surgical intervention in 41 patients with primary lung cancer. We evaluated individual lymph nodes by methionine PET along with corresponding CT images. The 11C-methionine accumulation of lymph nodes was assessed semiquantitatively by analysis of the tumor-to-muscle ratio (TMR) and was compared with CT and histological diagnoses. RESULTS: A total of 126 lymph nodes, 36 of which were histologically diagnosed as metastatic, were assessed by CT and methionine PET. The TMR in metastatic lymph nodes (n = 36) was 5.15+/-1.69, whereas that of nonmetastatic lymph nodes (n = 90) was 2.91+/-0.76; this difference was significant (P < 0.0001). The most adequate TMR cutoff value for diagnosis of metastasis based on the results of receiver operating characteristic curve analysis was 4.1. The positive and negative predictive values, sensitivity, specificity, and accuracy of methionine PET were 79.5%, 94.3%, 86.1%, 91.1%, and 89.7%, respectively, and were superior to those of CT (57.6%, P = 0.04; 81.7%, P = 0.008; 52.8%, P = 0.002; 84.4%, NS; and 75.4%, P = 0.002, respectively). All positive nodes that were shown to be true-positive by CT, and 12 of 17 false-negatives on CT were correctly diagnosed by PET. Ten of 14 lymph nodes that were false-positive on CT were also correctly diagnosed by PET. CONCLUSION: Methionine PET appears to be superior to CT for the diagnosis of lymph node metastasis in lung cancer patients. The high negative predictive value of methionine PET suggests that cases in which lymph nodes are enlarged on CT with negative PET analysis may be diagnosed as negative for metastasis.

Carbon Radioisotopes↗
PubMed2000

[Atherosclerosis-related aortic dissection].

Penetrating atherosclerotic aortic ulcers (PAU) can cause aortic dissection. Of 38 autopsy cases with aortic dissection, 6 (15.8%) had severe atherosclerotic changes, resembling those of PAU, at the site of entry (SE). Clinicopathological data on these patients were compared with those on 32 cases with nonatheromatous dissection (5 with Marfan syndrome or its forme fruste and 27 without Marfan syndrome) and 13 with atherosclerotic saccular aneurysms. For control study, the aorta of a 44-year-old woman who died of pulmonary cancer was used. Compare to nonatheromatous dissection, atherosclerosis-related aortic dissections were found in older women. Four cases were complicated by saccular aneurysms of the aorta. The SE was located in the ascending aorta in 1 and the descending aorta in 5. These sites usually were ulcerated atheromatous plaques or longitudinal fissures rather than transverse tears. Immunohistochemical examination of the SE revealed that MMP-1, 2, 9 and TIMP-2 were expressed in macrophages and/or interstitium, similar to the findings in atheromatous plaque or PAU. We propose that atherosclerosis-related aortic dissection differs from the usual classical aortic dissection. Patients with this lesion have a high risk of re-dissection from the new SE in the same lesion.

Adult↗
PubMed2000

[A randomized trial of conventional dose vs reduced dose in BHAC-DM therapy for acute myelogenous leukemia in elderly patients].

Twenty-nine patients aged 60-75 years with newly diagnosed acute myelogenous leukemia (AML) were randomized to receive BHAC-DM either at a reduced dose (S-1 group, n = 13; BHAC 150 mg/m2 1-7 day, DNR 30 mg/m2 1-3 day, 6MP 70 mg/m2 1-7 day) or the conventional dose (S-2 group, n = 16; BHAC 200 mg/m2 1-7 day, DNR 40 mg/m2 1-3 day, 6MP 70 mg/m2 1-7 day). On day 7, patients were given therapy for 2 more days if the ratio of blasts in their bone marrow was more than 15%. Granulocyte-colony stimulating factor was injected when the leukocyte count decreased below 1,000/microliter. The rates of complete remission were 46.2% in the S-1 group and 43.8% in the S-2 group. No significant differences in response distinguished the 2 groups. The mortality rate during myelosuppression was 1/13 in the S-1 group and 1/16 in the S-2 group. The rate of treatment-related death was 10.1% for all patients. Grade-4 adverse effects were not seen in any of the patients. We concluded that the conventional dose of BHAC-DM was as acceptable as the reduced dose in elderly patients with AML.

Aged↗
PubMed2000

Efficacy of a new formulation of lenograstim (recombinant glycosylated human granulocyte colony-stimulating factor) containing gelatin for the treatment of neutropenia after consolidation chemotherapy in patients with acute myeloid leukemia.

The efficacy and safety of a new formulation of lenograstim (recombinant glycosylated granulocyte colony-stimulating factor) prepared by switching the stabilizer from human serum albumin (HSA) to gelatin was investigated for the treatment of neutropenia after consolidation chemotherapy in patients with acute myeloid leukemia (AML). The results obtained in the study using the gelatin-containing formulation (gelatin-lenograstim) were retrospectively compared to those obtained from a placebo-controlled double-blind randomized study (AML-DBT) using the HSA-containing formulation (HSA-lenograstim). The median time of neutrophil recovery to > or = 1000/mm3 was significantly shorter in the gelatin-lenograstim group (14 days) than in the placebo group (21 days, P = .0001), and there was no significant difference between the gelatin-lenograstim group and the HSA-lenograstim group (14.5 days of AML-DBT, P = .5462). The incidences of febrile neutropenia were significantly reduced in the gelatin-lenograstim group (24/43, 55.8%) compared to the placebo group (58/64, 90.6%, P < .0001). The incidence of fever and antibiotic use was also significantly lower in the gelatin-lenograstim group (69.8% and 83.7%, respectively) than in the placebo group (92.2%, P = .0034, and 96.9%, P = .0285, respectively). However, between the 2 groups there were no differences in the number of patients who had infectious episodes. No serious adverse drug reactions ascribed to gelatin-lenograstim were encountered. These results demonstrate that gelatin-lenograstim exerted beneficial effects in the acceleration of neutrophil recovery and in the reduction of fever, febrile neutropenia, and antibiotic use, and its efficacy was equivalent to HSA-lenograstim. Therefore, we concluded that the gelatin-lenograstim formulation, which offers no risk of virus contamination and can be stored at room temperature, is more beneficial than the HSA-lenograstim formulation.

Acute Disease↗
PubMed2000

Ki-ras point mutation and p53 expression in human pancreatic cancer: a comparative study among Chinese, Japanese, and Western patients.

The aim of this study was to clarify features of Ki-ras point mutation (PM) and p53 expression in Chinese pancreatic cancer and to compare those with that in other countries. Dot blot hybridization and immunohistochemical methods were performed in 59 Chinese patients. The results showed that Ki-ras PMs at codon 12 and p53 expression were frequent in this group. No relationships were found between Ki-ras PM alone and p53 expression alone, and clinicopathological parameters, including age, gender, clinical stage, and histological grade and classification in Chinese patients. However, their cooperation was significantly associated with a poor prognosis in this group. Comparison showed that there were significant differences in the overall frequency and substitution of Ki-ras PM and in the ratio of transition:transversion in pancreatic cancer among various countries. In addition, the effect of Ki-ras PM and p53 expression on a poor prognosis of pancreatic cancer may be different among various countries. These findings suggested that not only Ki-ras PM and p53 expression are frequent in Chinese pancreatic cancer, but also a gene component to pancreatic cancer may be different between Asian and Western pancreatic cancer. In addition, it seems that cooperation of Ki-ras PM and p53 expression may predict a poor prognosis in Chinese patients with pancreatic cancer.

Adult↗
PubMed2000

[Pathology of xenograft, allograft and autograft cardiac valves].

Histopathological changes in xenograft, allograft and autograft heart valves after implantation are discussed. Collagen is the most important structural element in all these valves. In xenograft, there is no synthetic or renewal mechanism to replace the collagen that is gradually broken down, either because of proteolysis or the mechanical stresses to which the cusps are subjected. Thus, the cumulative effect of this breakdown can lead to the formation of cuspal tears and perforations. Collagen in implanted xonografts tends to undergo a time-dependent process of focal calcification, which may result in stenosis and/or regurgitation and loss of mobility of the cusps. In cryopreserved allograft, the viability of donor cells is usually not sufficient to maintain the structure of the cusps. The durability of allograft is influenced by the degree of preservation of collagen and elastic fibers in the graft, attenuation of immunologic reaction and extent of fibrous sheathing. Pulmonary autografts keep their cellular population and structure after implantation, and may have growth potential. Progressive root dilatation is the most important cause of valvular failure after the Ross procedure.

Animals↗
PubMed2000

Salmonella typhimurium DT104 from livestock in Japan.

We examined the distribution of multidrug-resistant Salmonella enterica serotype Typhimurium definitive phage type 104 (DT104) among Japanese livestock from 1973 to 1998. The 144 S. Typhimurium field isolates were tested for susceptibility to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline, kanamycin, trimethoprim, nalidixic acid, and norfloxacin. Thirty-six of 68 strains which exhibited resistance to five or more antimicrobials (ACSSuT+) were identified as DT104. Results of plasmid profiling showed that all DT104 strains retain a 90-kb virulence plasmid, while 20 of 36 strains possessed a few additional small plasmids ranging from 2 to 4 kb. These results showed that DT104 strains have existed in Japanese livestock since 1990, and that this phage type may be an important pathogen for cattle in Japan.

Animals↗
PubMed2000

[Evaluation of the activity and effects of combinations of various antibacterial agents against methicillin-resistant Staphylococcus aureus in vitro].

MICs of various antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA) were measured. Furthermore, we evaluated the effects of combinations of antibacterial agents against MRSA in vitro. In 24 cases out of 37, in which MRSA was isolated from inpatients, other microorganisms, such as Candida spp., Entrococcus spp., and Pseudomonas aeruginosa, were simultaneously isolated. From the results of minimum inhibitory concentrations (MICs), obtained from micro broth-dilution method, of various antibacterial agents against MRSA, range of MICs of arbekacin (ABK), vancomycin (VCM) and teicoplanin (TEIC) were < or = 0.25-4.0, 0.5-1.0 and 0.25-4.0 micrograms/ml respectively, and no strains of MRSA showed resistance to ABK, VCM and TEIC, so that we concluded that these three antibacterial agents were effective for MRSA infection. On the in vitro study of combination-effect of antibacterial agents, significant synergistic effects were achieved in the combination of VCM and flomoxef (FMOX) (Synergism rate was 97.3%) or VCM and imipenem (IPM) (Synergism rate was 97.2%). From the results that the fractional inhibitory concentration index in the combination of VCM with IPM was smaller than that with FMOX and that P. aeruginosa or Enterococcus spp. were simultaneously isolated in high frequency in the MRSA-isolated cases, we thought that the combination of VCM with IPM is more useful, because IPM is effective against P. aeruginosa but FMOX is not.

Aminoglycosides↗
PubMed2000

[Combination chemotherapy with vinorelbine and other cytotoxic agents for advanced breast cancer patients--a protocol of vinorelbine plus AC regimens used by the Japan Vinorelbin Study Group].

A new generation type of vinca alkaloid, vinorelbine (VNR), is a promising agent for the treatment of breast cancer patients. As a first line treatment for metastatic breast cancer, combination chemotherapy including anthracyclines plus VNR has demonstrated a high response rate and tolerability. In addition, other VNR containing regimens, such as 5-fluorouracil plus VNR, produced a 64% response rate. This evidence suggests VNR-containing combination chemotherapy may be a promising first-line treatment for breast cancer patients. In Japan, VNR is not registered, but a late phase II study has been completed. An approximately 30% response rate was obtained with its use as a monotherapy. In addition, a phase I/II study of combination VNR plus AC (adriamycin + cyclophosphamide) has been conducted. At the present time, the results are being analyzed.

Antineoplastic Agents, Phytogenic↗
PubMed2000

Antitumor imidazolyl disulfide IV-2 causes irreversible G(2)/M cell cycle arrest without hyperphosphorylation of cyclin-dependent kinase Cdk1.

Aberrant function of redox-regulated proteins is a possible cause for cellular transformation and loss of cell cycle control. The small protein thioredoxin has oncogenic properties and controls cell cycle movement through G(1), S, and G(2)/M phases. The redox-active, asymmetrical 1-methylpropyl-2-imidazolyl disulfide (IV-2) has previously been shown to react with and inhibit thioredoxin activity in vitro, the proliferation of human tumor cells in culture, and the growth of tumors in mice. We now examined the effects of IV-2 on cell cycle progression. In synchronized tsFT210 mouse mammary carcinoma cells, IV-2 halted cells in mitosis. In asynchronously growing MCF-7 human breast cancer cells, IV-2 exclusively and irreversibly blocked cells in G(2)/M at concentrations that correlated with its growth inhibitory activity. Neither the closely related, less redox active 2-hydroxy-1-methylpropyl-2-imidazolyl disulfide (AIV-2), which differs from IV-2 only by an additional hydroxyl group, nor the symmetrical diallyl disulfide caused a G(2)/M arrest under these conditions. Furthermore, MCF-7 cells treated with IV-2 showed increased Cdk1 kinase activity and a decrease in Cdk1 tyrosine phosphorylation, indicating that IV-2 did not directly inhibit Cdk1 or Cdc25 activities. IV-2 did, however, increase Bcl-2 phosphorylation. These data suggest that the thioredoxin inhibitor IV-2, despite its simple structure, is able to target redox-sensitive processes that are critical for cell cycle progression through mitosis. The results are also consistent with a role of thioredoxin regulating cell cycle progression through G(2)/M.

Allyl Compounds↗
PubMed2000

Changes in atrial natriuretic peptide concentration and expression of its receptors after pneumonectomy in the rat.

Atrial natriuretic peptide (ANP) is a cardiac hormone which affects endothelial cell function through a receptor-mediated process. Pneumonectomy is a common thoracic surgical procedure that can cause pulmonary oedema in the remaining lung. Few reports have investigated the aetiology of this complication. The aim of this study was to determine the changes in ANP concentration and expression of its receptors following pneumonectomy as a possible aetiology for postpneumonectomy pulmonary oedema (PPE). We compared plasma ANP concentrations, cGMP concentrations, and natriuretic peptide receptor (NPR)-A mRNA and NPR-C mRNA expression in rat lung 3 h after pneumonectomy (n=5) or a sham operation (n=5). The ANP concentrations in plasma and lung tissue in the pneumonectomy group were significantly higher than in the control group (749.5 versus 202.7 pg x ml(-1), P<0.01; 33.1 versus 6.8 ng x g(-1) wet tissue, P<0.01 respectively). The level of ANP mRNA expression in the pneumonectomy group was significantly higher than in the control group (1.44 versus 0.41 relative ANP mRNA expression, P<0.05). The concentration of cGMP and the level of NPR-A mRNA expression were not significantly different between the pneumonectomy and control groups. The level of NPR-C mRNA expression in the pneumonectomy group was significantly higher than in the control group (4.17 versus 2.19 relative NPR-C mRNA expression, P<0.01). These findings suggest that changes in pulmonary ANP and NPR-C expression may contribute to the development of PPE in the remaining lung in the acute phase following pneumonectomy.

Animals↗
PubMed2000

Expression of renin-angiotensin system and extracellular matrix genes in cardiovascular cells and its regulation through AT1 receptor.

Angiotensinogen (AGT) is a unique substrate of the renin-angiotensin system and fibronectin (FN) is an important component of the extracellular matrix. These play critical roles in the pathophysiological changes including cardiovascular remodeling and hypertrophy in response to hypertension. This study was performed to examine the regulation of AGT and FN gene in cardiac myocytes (CMs) and vascular smooth muscle cells (VSMCs) in response to mechanical stretch. Mechanical stretch significantly increased the AGT mRNA expression in CMs, while these stimuli did not affect FN mRNA levels. On the other hand, mechanical stretch upregulated FN mRNA levels in VSMCs, whereas no increase in AGT mRNA levels was observed in response to stretch stimuli. An angiotensin II type 1 (AT1) receptor antagonist (CV11974) significantly decreased these stretch-mediated increases in mRNA level and promoter activity of the AGT and FN gene, whereas angiotensin II type 2 (AT2) receptor antagonist (PD 123319) did not affect the induction. These results indicate that mechanical stretch activates transcription of the AGT and FN gene mainly via AT1 receptor-pathway in CMs and VSMCs. Furthermore, mechanisms regulating AGT and FN gene seem to be different between CMs and VSMCs.

Angiotensin Receptor Antagonists↗
PubMed2000

Cloning and characterization of a cDNA encoding serine palmitoyltransferase in Arabidopsis thaliana.

The first and committed step in de novo sphingolipid synthesis is catalysed by serine palmitoyltransferase (EC 2.3.1.50), which condenses serine and palmitoyl-CoA to form 3-ketosphinganine in a pyridoxal-5'-phosphate-dependent reaction. We have isolated and characterized a cDNA clone from Arabidopsis thaliana that is homologous to yeast and mammalian LCB2. For a functional identification, the A. thaliana homologous cDNA was expressed in Escherichia coli, which resulted in significant production of new sphinganine in E. coli cells.

Acyltransferases↗
PubMed2000

Characterization of sphingolipid long-chain base kinase in Arabidopsis thaliana.

Sphingolipid long-chain base (LCB) kinase catalyses the phosphorylation of sphingolipid LCB to form LCB 1-phosphate. Based on sequence identity to a murine sphingosine kinase (murine SPHK1a), we isolated and characterized a LCB kinase-like cDNA in Arabidopsis thaliana. The deduced amino acid sequence of the homologous cDNA shows several regions that are highly conserved in LCB kinases from mouse, yeast, human and Caenorhabditis elegans. These regions are not similar to those of other known kinase families. For a functional identification, the homologous cDNA from A. thaliana was expressed in Escherichia coli, and LCB kinase activity was measured. The recombinant AtLcbk1 protein was found to utilize ATP and sphinganine. These results indicate the first identification of a gene coding for a LCB kinase in plants.

Arabidopsis↗
PubMed1999

Dual G1 and G2/M phase inhibition by SC-alpha alpha delta 9, a combinatorially derived Cdc25 phosphatase inhibitor.

The Cdc25 dual specificity phosphatase family has a central role in controlling cell cycle progression and has been implicated in the etiology of cancer. One compound, 4-(benzyl-(2-[(2, 5-diphenyl-oxazole-4-carbonyl)-amino]-ethyl)-carbamoyl)-2-decanoylami no butyric acid (SC-alpha alpha delta 9), was previously identified as the most potent reported synthetic inhibitor of Cdc25 phosphatases in vitro. In the present study, we demonstrate that SC-alpha alpha delta 9 inhibited Cdc25-dependent cell cycle progression at both G1 and G2/M phase using tsFT210 cells, which express a temperature-sensitive Cdc2 mutant. SC-alpha alpha delta 9 blocked both G2/M transition and dephosphorylation of Cdc2 in a concentration-dependent manner. SC-alpha alpha delta 9 also enhanced tyrosine phosphorylation of both Cdk2 and Cdk4, and decreased Cdk4 kinase activity. Both of the kinases are potent regulators of G1 transition. Furthermore, closely related chemical analogs that lacked Cdc25 inhibitory activity failed to block cell cycle progression at both G1 and G2/M, and did not affect Cdc2 phosphorylation or Cdk4 kinase activity. SC-alpha alpha delta 9 did not alter p53, p21 or p16 levels. Our results support the hypothesis that the disruption in cell cycle transition caused by SC-alpha alpha delta 9 was due to intracellular Cdc25 inhibition. We propose that the SC-alpha alpha delta 9 pharmacophore could be useful in further clarifying the role of Cdc25 phosphatase-dependent pathways in checkpoint control, oncogenesis, and apoptosis.

Cell Cycle↗
PubMed1999

Relation between QT interval dispersion and heart rate.

Because the relation between QT dispersion (QTd) and heart rate (HR) are different from that between QT interval and HR, QTd could be overadjusted at a high HR and be underadjusted at a slow HR if we use Bazett's formula to adjust QTd. HR adjustment of QTd is not needed to evaluate repolarization dispersion.

Aged↗