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Biomedical subjects

R Ishida

Publications and source records attributed to R Ishida.

At least 37 records · Page 2Linked to original sources
PubMed2001

Mitotic specific phosphorylation of serine-1212 in human DNA topoisomerase IIalpha.

It is known that topoisomerase IIalpha is phosphorylated by several kinases. To elucidate the role of phosphorylation of topoisomerase IIalpha in the cell cycle, we have examined the cell cycle behavior of phosphorylated topoisomerase IIalpha in HeLa cells using antibodies against several phospho-oligopeptides of this enzyme. Here we demonstrate that serine1212 in topoisomerase IIalpha is phosphorylated only in the mitotic phase. Using an antibody against an oligopeptide containing phosphoserine-1212 in topoisomerase IIalpha (PS1212), subcellular localization of topoisomerase IIalpha phosphorylated at serine1212 was examined by indirect immunofluorescence staining, and compared with that of overall topoisomerase IIalpha. Serine1212-phosphorylated topoisomerase IIalpha was localized specifically on mitotic chromosomes, but not on interphase chromosomes; this result contrasts with overall topoisomerase IIalpha which was observed on chomosomes in both interphase and mitosis. Serine1212-phosphorylated topoisomerase lIalpha first appeared on chromosome arms in prophase, became concentrated on the centromeres in metaphase, and disappeared in early telophase. In addition, ICRF-193, a catalytic inhibitor of topoisomerase II, prevented accumulation of serine1212-phosphorylated topoisomerase IIalpha at the centromeres. These results indicate that serine1212 of topoisomerase IIalpha is phosphorylated specifically during mitosis, and suggest that the serine1212-phosphorylated topoisomerase IIalpha acts on resolving topological constraint progressively from the chromosome arm to the centromere during metaphase chromosome condensation.

Antibodies, Monoclonal↗
PubMed2001

Study of quantitative oral radioactivity in salivary gland scintigraphy and determination of the clinical stage of Sjögren's syndrome.

UNLABELLED: In this study, the oral radioactivity seen in salivary gland scintigraphy, which was established entirely on the basis of radioactive saliva secreted by the parotid and submandibular glands, was evaluated quantitatively in healthy volunteers and in patients with Sjögren's syndrome. METHODS: Salivary gland scintigraphy and labial biopsy were performed on 70 patients with Sjögren's syndrome. After intravenous administration of 99mTc-sodium pertechnetate, dynamic scintigraphy was performed and time-activity curves for the oral cavity and four major salivary glands were generated. Lemon juice stimulation was delivered at 40 min. The prestimulatory oral activity index, poststimulatory oral activity index, and time interval between the vascular perfusion peak and the prestimulated maximum oral activity point were calculated to quantify the oral activity. Other glandular functional parameters-namely, maximum accumulation (MA), maximum secretion, secretion velocity, time at maximum count, time interval from stimulation to minimum count, and uptake ratio (UR) of the parotid and submandibular glands-were also calculated. Salivary gland scintigraphy was also performed on 21 healthy subjects with no evidence of salivary gland malfunction. RESULTS: Histopathologic grade 1 or 2 was found in 29 patients and grade 3 or 4 was found in 41 patients, and they were regarded as being in the early and advanced stages of Sjögren's syndrome, respectively. After overall analysis, all of the oral activity indices and the MA and UR of the submandibular gland clearly decreased as clinical severity progressed, and statistically significant differences were observed. CONCLUSION: New oral activity indices correlated with the stage of Sjögren's syndrome, and these quantitative oral indices together with certain glandular parameters (mainly MA and UR of the submandibular gland) were found to be sensitive enough to distinguish the disease severity of Sjögren's syndrome.

Biopsy↗
PubMed2001

Antitumor effects of a novel phenoxazine derivative on human leukemia cell lines in vitro and in vivo.

2-Amino-4,4alpha-dihydro-4alpha,7-dimethyl-3H-phenoxazine-3-one (Phx) was synthesized by reacting 2-amino-5-methylphenol with bovine hemolysates. Because Phx is a phenoxazine derivative like actinomycin D, we examined its effects on the proliferation of the human leukemia cell lines K562, HL-60, and HAL-01. Phx inhibited proliferation and induced apoptosis in all of the leukemia cell lines we tested, in a dose-dependent manner. We further investigated the antitumor effect of this compound on HAL-01-bearing nude mice. Treatment with Phx markedly reduced the tumor growth rate in the experimental group, as compared with the control group. Moreover, Phx was found to have few adverse effects on weight loss and WBC count. In addition, we examined the effects of Phx on human normal hematopoietic progenitor cells by a clonogenic assay, and we observed less suppression of normal progenitor cells than of leukemic progenitors. These results suggest that Phx may be used to treat patients affected by different types of leukemia.

Animals↗
PubMed2001

[Analysis of correlation between physical training and autonomic function by using multivariate analysis: establishing an indicator of health].

The purpose of this study is to assess the effects of physical training on autonomic nervous function. Twenty-two healthy subjects(12 males and 10 females) participated in this study. We inquired contents of the exercise for each subject. Continuous ECG was recorded during 320 seconds at supine resting. Respiratory rhythm was fixed at 0.25 Hz(15 time/min). On the basis of spectral analysis of heart rate variability, the autonomic nervous function was assessed by low frequency power(LF: 0.06-0.13 Hz) and high frequency power(HF: 0.16-0.50 Hz). The predominance of sympathetic nervous activity were indicated by the LF/HF and LF-HF. Relationship between physical training and autonomic function was analyzed by using multivariate analysis(partial correlation analysis). As the results, LF power and LF-HF negatively correlated with training time per day, energy expenditure per day, energy expenditure per week, and total energy expenditure, respectively(p < 0.05). HF power positively correlated with energy expenditure per day, energy expenditure per week, and total energy expenditure, respectively(p < 0.05). These results indicate not training time but energy expenditure alters the autonomic nervous function. This index may be useful for evaluating training effect on the promotion of health.

Adult↗
PubMed2000

Structural analysis of the gene encoding RP58, a sequence-specific transrepressor associated with heterochromatin.

RP58, a sequence-specific transcriptional repressor sharing homology with the POZ domain of a number of zinc-finger proteins, is highly synthesized in brain and localized in condensed chromatin regions, suggesting a role in transcriptional repression in the central nervous system. In the present study, genomic clones of the human rp58 gene were isolated to determine the complete genomic organization. Sequence analyses indicated that the human rp58 gene encoding the functional protein is uninterrupted over its entire 4.2 kb length. Comparison of the human and mouse rp58 genes revealed that they share not only a high homology in the amino acid sequences of their encoded proteins, but also a high degree of structural similarity at the genomic level. RT-PCR analysis also demonstrated the existence of an alternatively spliced form of rp58 similar to the previously reported zinc-finger cDNA, C2H2-171. Chromosomal mapping by fluorescence in situ hybridization analysis allowed localization of the rp58 gene to human chromosome 1q44 ter, a genetic region associated with a number of human malignancies and neurological disorders.

Alternative Splicing↗
PubMed2000

Reoperative coronary artery bypass via left thoracotomy.

The patient was a 49-year-old woman. When she was 39 years old, she underwent coronary artery bypass grafting (left internal thoracic artery to left anterior descending artery, saphenous vein graft to first diagonal branch). At the age 48, she had effort angina. On coronary angiography, triple-vessel disease was found, and she was treated conservatively. Progression of the disease was confirmed with detection of the left circumflex artery associated with jeopardized collateral to the right coronary artery showing total occlusion. The patient underwent reoperation. Since the left internal thoracic artery was patent despite occlusion of the saphenous vein graft, the approach of left thoracotomy was employed. Under cardiopulmonary bypass with ventricular fibrillation and left vent through left atrial appendage, the right radial artery was anastomosed to the left circumflex artery from the descending thoracic aorta, and the right gastroepiploic artery was anastomosed to the right coronary artery (4AV branch). Patency of the bypass was confirmed postoperatively. We consider this operative technique was especially useful for reoperation in cases of a patent internal thoracic artery in which left thoracotomy can be conducted safely.

Coronary Artery Bypass↗
PubMed2000

Zinc induces mixed types of cell death, necrosis, and apoptosis, in molt-4 cells.

To investigate the mode of zinc-induced cell death, the associated morphological changes, and biological events were examined in zinc-treated Molt-4 cells. Fluorescence microscope observations with double staining of zinc-treated cells with Hoechst 33342 and propidium iodide (PI) indicated that the metal induced both necrosis and apoptosis. To confirm this, cells were stained with both PI and FITC-labeled annexin V, which binds phosphatidylserine, and then analyzed by flow cytometry. The results also confirmed that zinc induces mixed types of cell death, necrosis and apoptosis, and that the former induction occurs earlier and at a greater frequency. Hallmarks of apoptosis such as abnormal chromosome condensation and release of cytochrome c, as well as the appearance of annexin-positive cells, appeared along with the expression of mitochondrial membrane protein 7A6. However, zinc did not induce increases in caspase-3 like protease and caspase-8 activities, and caused slightly hypodiploid cells. Furthermore, the induction of cell death and annexin-positive cells was not blocked by the caspase inhibitors Ac-YVAD-CHO and Ac-DEVD-CHO. These results indicate that zinc induces both necrosis and apoptosis, without caspase-3 activation.

Apoptosis↗
PubMed2000

Antitumor activity of 2-amino-4,4alpha-dihydro-4alpha, 7-dimethyl-3H-phenoxazine-3-one against Meth A tumor transplanted into BALB/c mice.

We examined the in vivo effect of 2-amino-4,4alpha-dihydro-4alpha,7-dimethyl-3H-phenoxazine-3- one (Phx) on Meth A carcinoma cells transplanted into BALB/c mice, in terms of both antitumor activity and side effects. Phx, which was synthesized by the reaction of 2-amino-5-methylphenol with bovine hemolysates, was administered i.p. at doses of 1 and 5 mg/kg to BALB/c mice transplanted with Meth A tumor cells. Phx exerted a strong antitumor activity to Meth A tumor growing in the mice as 5-fluorouracil (5-FU) did. The antitumor activity of Phx at the dose of 5 mg/kg was comparable to that of 5-FU at the dose of 7.8 mg/kg. In contrast, unlike 5-FU, Phx did not cause leukopenia while showing a strong antitumor activity. The compound also produced little changes in body weight and no wasting of mice developed. These results show that Phx has strong anti-tumor activity, but exerts lower side effects and suggest that Phx is available for therapeutic purposes in the future.

Animals↗
PubMed2000

Comparison of lung perfusion scintigraphic findings in pulmonary thromboembolism in systemic lupus erythematosus, SLE plus antiphospholipid syndrome, and primary antiphospholipid syndrome.

In this study, we compared and reviewed the findings on lung perfusion scans performed in patients with systemic lupus erythematosus (SLE), systemic lupus erythematosus with associated antiphospholipid syndrome (SLE + APS), and primary antiphospholipid syndrome (PAPS), to evaluate the prevalence of pulmonary embolism in restricted samples of the patient groups. Lung perfusion scintigraphy with 99Tc(m)-macroaggregated albumin was performed in 31 patients (SLE = 7; SLE + APS = 14; PAPS = 10). The seven patients with SLE alone and the 10 patients with PAPS had normal perfusion lung scans. Six of the 14 SLE + APS patients showed a segmental uptake defect on multi-view perfusion scans. Thus, the SLE + APS patients were found to have a higher risk of pulmonary thromboembolism than the SLE alone and primary APS patients (P<0.05). The results of our study suggest that lung perfusion scintigraphy should be performed routinely in these patients, even in the absence of pulmonary clinical manifestations, to obtain baseline data for disease outcome and management.

Adult↗
PubMed2000

Thallium-201 myocardial SPET in patients with collagen disease.

We analysed stress 201Tl myocardial single photon emission tomography (SPET) in collagen disease patients to evaluate abnormal uptake patterns and their clinical significance in the assessment of the cardiac status of these patients. The main purpose of the study was to evaluate the clinical significance of reverse redistribution. Twenty-two collagen disease patients (13 with progressive systemic sclerosis (PSS) and nine with systemic lupus erythematosus (SLE)) were examined by 201Tl myocardial SPET with exercise (n = 9) or dipyridamole stress (n = 13). For quantitative analysis, each 201Tl SPET polar map was divided into 17 segments, and the 201Tl uptake pattern of each segment was classified into four types. Eighteen (82%) of the patients showed abnormal findings on 201Tl SPET. Of the 374 segments analysed, 295 (79%) were classified as normal, 16 (4%) as reverse redistribution, 49 (13%) as reversible defect and 14 (4%) as fixed defect. Patients were divided into two groups: those with cardiac abnormalities on conventional testing (Group A, n = 10) and those without (Group B, n = 12). The incidences of fixed defect, reversible defect and reverse redistribution were significantly higher (P <0.01, P <0.0005, P <0.05, respectively) in Group A than in Group B. Nine (90%) of the patients in Group A and nine (75%) in Group B showed abnormal findings. No significant difference was found between the PSS and SLE patients in the incidence of the individual uptake patterns. Stress 201Tl myocardial SPET appears to be an effective method of evaluating a wide spectrum of myocardial involvement in collagen disease patients and in assessing their clinical cardiac status. Reverse redistribution is found to be a significant finding in collagen disease patients.

Adolescent↗
PubMed1999

Decreased thymosin beta4 in apoptosis induced by a variety of antitumor drugs.

As many antitumor drugs can kill tumors through the induction of apoptosis, the effect of these drugs presumably would be enhanced if they were used in combination with other drugs that interact with apoptotic processes. To clarify the biological events involved in the induction of apoptosis, we examined changes in the proteins associated with induction of apoptosis by antitumor drugs. When Molt-4 cells were exposed to the antitumor drugs etoposide, meso-2,3-bis(3,5-dioxopiperazine-1-yl)butane (ICRF-193), and neocarzinostatin, they exhibited apoptotic cell death as determined by flow cytometry using fluorescein isothiocyanate (FITC)-labeled annexin V staining of phosphatidylserine on membranes and detection of hypodiploid cells. Following the induction of apoptosis, a low molecular weight protein that was identified to be thymosin beta4 by HPLC analysis was commonly decreased, and the morphology of actin filaments changed into clump formations. These results suggest that decreased thymosin beta4 is involved in the induction of apoptosis by antitumor drugs.

Actins↗
PubMed1999

The DNA binding activity of Translin is mediated by a basic region in the ring-shaped structure conserved in evolution.

DNA binding proteins, for the most part, function as dimers or tetramers which recognize their target sequences. Here we show that Translin, a novel single-stranded DNA end binding protein, forms a ring-shaped structure conserved throughout evolution and that this structure is responsible for its DNA binding activity. Point mutations at Leu184 and Leu191 in the leucine zipper motif of human Translin resulted in loss of the multimeric structure and abrogation of DNA binding. Point mutations at R86, H88, H90 to T86, N88, N90 in one of the basic regions, however, completely inhibited the DNA binding activity without affecting the multimeric structure. These results support the view that the DNA binding domain of Translin is formed in the ring-shaped structure in combination with its basic region (amino acids 86-97) polypeptides.

Amino Acids↗
PubMed1999

67Ga whole-body scintigraphy in the evaluation of head and neck squamous cell carcinoma.

The diagnostic accuracy of 67Ga-citrate whole-body scintigraphy for the evaluation of primary tumours, local recurrences, cervical node metastases and distant metastases was investigated in patients with head and neck squamous cell carcinoma (SCC). Altogether, 102 67Ga-citrate whole-body scans were performed on 83 patients with head and neck SCC using a dual-headed gamma camera. The results were compared with those of computed tomography (CT) and final diagnosis. 67Ga scintigraphy correctly diagnosed 28 of 29 primary lesions, a sensitivity of 97% (CT = 97%). For tumour recurrence, 67Ga scintigraphy correctly diagnosed 13 of 15 recurrences and 53 of 58 instances of no recurrence, giving a sensitivity of 87% and a specificity of 91% (CT = 80 and 62%, respectively). Scintigraphy correctly diagnosed 23 of 31 metastatic sides of the neck and all 173 negative sides of the neck, giving a sensitivity of 74% and a specificity of 100% (CT = 90 and 84%, respectively). Finally, scintigraphy correctly diagnosed all 12 distant metastases as well as 86 of 90 cases of no metastasis, resulting in a sensitivity of 100% and a specificity of 96%. Furthermore, in five patients, distant metastases were initially detected on 67Ga scintigraphy. In conclusion, 67Ga whole-body scintigraphy with a dual-headed camera resulted in a high sensitivity and specificity for the detection of primary lesions, recurrences and distant metastases of head and neck SCC. Although the sensitivity for detecting neck node metastases was relatively low, the specificity was high. Thus, 67Ga scintigraphy is an effective technique for the evaluation of head and neck SCC, especially tumour recurrence and distant metastases.

Adolescent↗
PubMed1998

RP58 associates with condensed chromatin and mediates a sequence-specific transcriptional repression.

An approximately 120-amino acid domain present generally at the NH2 termini, termed the POZ domain, is highly conserved in various proteins with zinc finger DNA binding motifs. We have isolated a novel protein sharing homology with the POZ domain of a number of zinc finger proteins, including the human BCL-6 protein. By using a binding site selection technique (CAST), a high affinity binding site of the protein was determined to be (A/C)ACATCTG(G/T)(A/C), containing the E box core sequence motif. The protein was shown to repress transcription from a promoter linked to its target sequences and was hence named RP58 (Repressor Protein with a predicted molecular mass of 58 kDa). Immunogold electron microscopic study revealed that almost all RP58 is localized in condensed chromatin regions. These observations demonstrate for the first time that a protein mediating a sequence-specific transcriptional repression associates with highly condensed chromatin. We suggest that RP58 may be involved in a molecular link between sequence-specific transcriptional repression and the organization of chromosomes in the nucleus.

Amino Acid Sequence↗
PubMed1998

Catalytic inhibitors of DNA topoisomerase II.

Catalytic inhibitors of mammalian DNA topoisomerase II have been found recently in natural and synthetic compounds. These compounds target the enzyme within the cell and inhibit various genetic processes involving the enzyme, such as DNA replication and chromosome dynamics, and thus proved to be good probes for the functional analyses of the enzyme in a variety of eukaryotes from yeast to mammals. Catalytic inhibitors were shown to be antagonists against topoisomerase II poisons. Thus bis(2,6-dioxopiperazines) have a potential to overcome cardiac toxicity caused by potent antitumor anthracycline antibiotics such as doxorubicin and daunorubicin. ICRF-187, a (+)-enantiomer of racemic ICRF-159, has been used in clinics in European countries as cardioprotector. Furthermore, bis(2,6-dioxopiperazines) enhance the efficacy of topoisomerase II poisons by reducing their side effects in preclinical and clinical settings. Bis(2,6-dioxopiperazines) per se among others have antitumor activity, and one of their derivatives, MST-16 or Sobuzoxane, bis(N1-isobutyloxycarbonyloxymethyl-2, 6-dioxopiperazine), has been developed in Japan as an anticancer drug used for malignant lymphomas and adult T-cell leukemia in clinics.

Antineoplastic Agents↗