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T Nemoto

Publications and source records attributed to T Nemoto.

At least 109 records · Page 6Linked to original sources
PubMed1996

Dimerization characteristics of the 94-kDa glucose-regulated protein.

The 94-kDa glucose-regulated protein (GRP94) is a member of the 90-kDa heat-shock protein (HSP90) family. In this study, we expressed the barley (Hordeum vulgare L.) GRP94 and the alpha isoform of human HSP90 (HSP90 alpha) in Escherichia coli and compared their dimer-forming abilities. Native polyacrylamide gel electrophoresis revealed that GRP94 (amino acids 69-809) and the full-length form of HSP90 alpha existed in the dimeric state. The C-terminal 326 amino acids of GRP94 or the C-terminal 200 amino acids of HSP90 alpha were sufficient for the dimerization. Limited proteolysis of the C-terminal half of GRP94 with thrombin revealed a 16-kDa fragment, which was derived from the C-terminus of GRP94 through the cleavage of either the Arg710-His711 or the Arg735-Leu736 bond. These cleavage sites were nearly, if not completely, equivalent to the proteolyzed region of HSP90 alpha. Their structural similarity prompted us to investigate, by use of a coexpression system, the possibility that the two proteins form a heterodimeric complex. A two-step affinity chromatography that specifically trapped only the complex revealed that the C-terminal 200 amino acids of HSP90 alpha and the C-terminal 326 amino acids of GRP94 associated with HSP90 alpha and GRP94, respectively. However, the C-terminal 326 amino acids of GRP94 failed to form a complex with HSP90 alpha. In conclusion, these results indicate the similarity of the general dimeric conformation of the two HSP90 family member proteins, but show that the similarity is not sufficient to allow heterodimer formation.

Amino Acid Sequence↗
PubMed1996

Effects of gonadotropin-releasing hormone agonist (GnRHa) and ovariectomy on leukocyte subpopulations in rats with autotransplanted endometrium.

PROBLEM: To determine the effect of estrogen deficiency on populations of immune cells in rats with autotransplanted endometrium. METHOD OF STUDY: Autologous endometrial segments were implanted in the peritoneum of rats. Leukocyte subsets in the peripheral blood (PB) and peritoneal fluid (PF) of autotransplanted rats treated with gonadotropin-releasing hormone agonist (GnRHa) or ovariectomy were analyzed by flow cytometry. RESULTS: Endometrial growth was suppressed in association with increases in natural killer (NK) cells and macrophages in rats treated surgically or medically after endometrial implantation compared with autotransplanted-only rats. Normal rats treated with GnRHa showed no significant alterations in PB and PF leukocyte subsets, even in NK cells and macrophages, compared with untreated normal rats. CONCLUSIONS: Data suggest that GnRHa itself did not have an immunomodulating effect when rats were treated for 3 weeks, but that a hypoestrogenic state reduced the size of the ectopic endometrium in association with increases in NK cells and macrophages. Our findings support the hypothesis that ectopic endometrial cells may release immunosuppressive factors.

Animals↗
PubMed1996

The fission yeast sts5+ gene is required for maintenance of growth polarity and functionally interacts with protein kinase C and an osmosensing MAP-kinase pathway.

Cell morphogenesis is a fundamental phenomenon that involves understanding a number of biological processes including the developmental program, polarity and cell division. Fission yeast sts5 mutant cells are round rather than cylindrical with cortical actin randomly dispersed. Genetic analyses demonstrate that the sts5+ gene is required for maintenance of cell shape during interphase when the cell normally exhibits polarised growth. The sts5 mutant is not defective in cell wall integrity. Deletion of ppe1+, which encodes a type 2A-like protein phosphatase, shows similar phenotypes to the sts5 mutant and these two mutations are synthetically lethal. Multicopy plasmids containing either the protein kinase C-like gene pck1+ or the protein tyrosine phosphatase pyp1+, an inhibitor of an osmosensing Sty1/Spc1 MAP-kinase, are capable of suppressing the sts5 mutation. Consistent with this, we have found that the wis1 mutation, which is defective in a MAP-kinase kinase of the pathway, suppresses the sts5 mutation. The predicted sts5+ gene product exhibits sequence similarity to two yeast proteins, Dis3 and Ssd1 and a nematode protein, F46E8.6, where the former two yeast proteins have been shown to be involved in cell cycle control and cell morphogenesis. The sts5+ gene is not essential for cell viability, but is absolutely required for polarised growth as the gene disruption showed the same phenotypes as those of the original mutants. Overexpression of the sts5+ gene resulted in altered cell morphology and, cortical actin in these overproducing cells was also abnormal, fainter and often dispersed. Anti-Sts5 antibody specifically detected a 130 kDa protein by western blotting. A green fluorescent protein-Sts5 fusion protein localised in the cytoplasm with a discrete punctate pattern, suggesting that the Sts5 protein is a component of a novel structure. These results have indicated that the Sts5 protein is a crucial determinant of polarised growth and that it functionally interacts with the serine/threonine phosphatase, protein kinase C, and an osmosensing MAP-kinase to maintain cell morphology.

Amino Acid Sequence↗
PubMed1996

[Clinical significance of additional ST segment elevation immediately after successful reperfusion in patients with anterior wall acute myocardial infarction].

The clinical significance of additional ST segment elevation immediately after reperfusion in acute myocardial infarction (AMI) is still unclear. The influence of additional ST elevation on myocardial damage was examined in 62 patients with first anterior AMI. All patients had coronary reflow (thrombolysis in myocardial infarction: TIMI grade III) within 6 hours after the onset of infarction and no subsequent reocclusion for at least 14 days. The patients were classified into two groups: group ST (+), 26 patients with additional ST elevation (> or = 5 mm increase in sigma ST in lead V1-V6) immediately after reperfusion, and group ST(-), 36 patients without additional ST elevation. Myocardial damage was estimated by the number of abnormal Q wave before and 1 hour after reperfusion (nQpre and nQpost. There were no significant differences in the elapsed time, ECG indexes before reperfusion and regional wall motion (RWM: SD/chord; SD = standard deviation) in the acute phase and 14 days after the onset between the two groups. Moreover, within each group the patients were classified into two groups on the basis of RWM 14 days after the onset: group A = RWM < -2.5 in group ST (+) (n = 17); group B = RWM > or = -2.5 in group ST(+) (n = 9); group C = RWM < -2.5 in group ST (-) (n = 14); group D = RWM > or = -2.5 in group ST(-) (n = 22). There were no significant differences in the elapsed time between the four groups. nQpre was highest in group C and was lowest in group D (group A: 2.1, group B: 1.9, group C: 4.1, group D: 1.4), and nQpost was highest in group C and group A, and was lowest in group D (group A: 4.1, group B: 2.7, group C: 4.4, group D: 2.0). There was a significant increase in nQ after reperfusion (nQpost-nQpre) in group A and group B, which was greater in group A than in group B. The increase in sigma ST after reperfusion was greater in group A than in group B. There was no significant increase in nQ after reperfusion in group C and in group D, and both nQpre and nQpost were highest in group C, and lowest in group D. Infarct size was larger in group A and in group C than group B and group D, and there was no significant improvement in RWM in group A and in group C. In conclusion, additional ST elevation immediately after reperfusion seems to occur in patients with not so severe myocardial damage before reperfusion, and may reflect reperfusion injury. Additional ST elevation is not observed in patients with preceding extensive myocardial damage which may be irreversible or not still advanced at the time of reperfusion.

Adult↗
PubMed1995

Interferon modulates the messenger RNA of G1-controlling genes to suppress the G1-to-S transition in Daudi cells.

Interferon (IFN) is one of the potent antiproliferative cytokines and is used to treat some selected cancers. IFN arrests the growth of Burkitt Lymphoma derived cell line Daudi cells in the G1 phase. G1-to-S progression is controlled by positive and negative regulatory genes. Therefore, we investigated the effects of IFN on G1-controlling genes. Expression of cyclin-dependent kinases (Cdks 2, 3, 4, 5, 6), MO15/Cdk7, and cyclins E and H was studied to assess positive regulators, while p15Ink4B, p16Ink4, p18, p21Cip1, and p27Kip1 were assessed as negative regulators. Cdks 2, 4, 6 and cyclin E were markedly down-regulated. MO15/Cdk7 expression showed little change, but its regulatory subunit (cyclin H) was down-regulated like cyclin E. Expression of p15Ink4B and p16Ink4 was not observed. p18 was induced until 48 h and its expression returned to the initial level at 72 h. In contrast, p21Cip1 mRNA expression remained at the baseline level throughout IFN treatment, while the expression of p27Kip1 increased at 48 and 72 h. Taken together, these data indicate that IFN changes the messenger RNA of G1-controlling genes towards the suppression of G1-to-S transition.

Base Sequence↗
PubMed1995

Mechanism of dimer formation of the 90-kDa heat-shock protein.

This study describes the mechanism of homodimer formation of the 90-kDa heat-shock protein (HSP90). In eukaryotic cells, there are two HSP90 isoforms, alpha and beta, encoded by two separate genes. HSP90 alpha exists predominantly as a homodimer, HSP90 beta mainly as a monomer. Analysis by native PAGE revealed that bacterially expressed HSP90 alpha fused to glutathione S-transferase (GST) existed as a high-molecular-mass oligomer, and was converted to a homodimer following removal of the fusion enzyme by thrombin cleavage. A deletion mutant, HSP90 alpha D44-603, formed a monomer and an N-terminal truncated mutant, HSP90 alpha 533-732, existed as a dimer, indicating that the dimer-forming ability resides somewhere in the C-terminal 200 amino acids. Limited proteolysis of the C-terminal 200 amino acids of HSP90 alpha with chymotrypsin produced the C-terminal 16-kDa fragment (Met628/Ala629-Asp732) and its adjacent more N-terminal 13-kDa fragment (Val542-Tyr627/Met628). Size-exclusion HPLC and two-dimensional PAGE analyses demonstrated that these two chymotryptic fragments bound each other. The C-terminal 198 amino acids as well as the full-length form of HSP90 beta revealed a lower dimer-forming activity than HSP90 alpha. Expression of the chimeric proteins at the C-terminal 198 amino acids of the alpha and beta isoforms further indicated that the 16 amino acid substitutions locating between amino acids 561 and 685 account for the impeded dimerization of HSP90 beta. A leucine zipper motif (Met402-Leu423) was unlikely to be involved in the dimer formation. Taken together, these results indicate that the dimeric structure of HSP90 alpha is mediated by the C-terminal 191 amino acids and consists of duplicate interactions of the C-terminal region (Met628/Ala629-Asp732) of one subunit and the adjacent more N-terminal region (Val542-Try627/Met628) of the other subunit.

Amino Acid Sequence↗
PubMed1995

Stochastic behavior of organelle motion in Nitella internodal cells.

The stochastic behavior of organelles during the recovery process of protoplasmic streaming is investigated in Nitella internodal cells at a nanometer space resolution. The motions of organelles in the components parallel and perpendicular to the alignment of actin filaments in the cell are analysed from the traces of displacement of 860 organelles in 1/30s (= video rate). The analysis of those traces shows that the generation of motive forces to the organelle follows the Poisson process. Therefore, we have been able to estimate the step size corresponding to the single force generation as approximately 100 nm.

Actins↗
PubMed1995

Cytochrome P4501A1 and glutathione S-transferase (M1) genetic polymorphisms and postmenopausal breast cancer risk.

Polycyclic aromatic hydrocarbons, possible human breast carcinogens, are metabolized by cytochrome P4501A1 (CYP1A1) and glutathione S-transferase (GSTM1). A CYP1A1 polymorphism (isoleucine to valine substitution in exon 7) or the null allele for GSTM1 may affect the mutagenic potential of polycyclic aromatic hydrocarbons. We examined polymorphisms in GSTM1 and CYP1A1 in relation to breast cancer risk. Included were 216 postmenopausal Caucasian women with incident breast cancer and 282 community controls. DNA analyses suggested no increased breast cancer risk with the null GSTM1 genotype [odds ratio (OR) = 1.10; CI, 0.73-1.64], although there was some indication that the null genotype was associated with risk among the youngest postmenopausal women (OR = 2.44; CI, 0.89-6.64). Slightly elevated risk was associated with the CYP1A1 polymorphism (OR = 1.61; CI, 0.94-2.75) and was highest for those who smoked up to 29 pack-years (OR = 5.22; CI, 1.16-23.56). Statistical power to detect an effect may be limited by small numbers, and larger sample sizes would be required to corroborate these suggestive findings.

Age Factors↗
PubMed1995

Synaptic contact of neuropeptide-and amine-containing axons on parasympathetic preganglionic neurons in the superior salivatory nucleus of the rat.

Parasympathetic preganglionic neurons in the superior salivatory nucleus (SSNNs) projecting to the pterygopalatine ganglion were labeled by retrograde transport of cholera toxin B subunit (CTB) in the rat. Morphological interactions between SSNNs and afferent fibers immunoreactive (IR) for neuropeptide and amine were examined with light and electron microscopes by double-immunostaining techniques. SSNNs were found in the ipsilateral ventrolateral part of the rostral medulla oblongata. Around SSNNs, substance P-, enkephalin-, neuropeptide Y-and somatostatin-IR nerve fibers were very rich and tyrosine hydroxylase (TH)-, serotonin (5-HT)-, vasoactive intestinal polypeptide- and calcitonin gene-related peptide (CGRP)-IR axons showed moderate density. Thyrotropin-releasing hormone-containing axons were scarce in this region. The electron microscopic examinations revealed that CTB-IR structures directly received synaptic input from axon varicosities IR for TH, 5-HT and all neuropeptides except for CGRP. These findings suggest that catecholamine, 5-HT and the neuropeptides directly influence the activity of SSNNs and are concerned with the autonomic regulation of nasal and palatal mucosa, lacrimal glands and cerebral blood vessels of the rat.

Afferent Pathways↗
PubMed1995

A macrolide antibiotic, roxithromycin, inhibits the growth of human myeloid leukemia HL60 cells by producing multinucleate cells.

The antiproliferative effect of roxithromycin (RXM) was studied using human myeloid leukemia HL60 cells. RXM inhibited the growth of HL60 cells in a concentration-dependent manner, and significantly inhibited growth at concentrations above 75 microM. This growth inhibition was not associated with specific cell cycle arrest and DNA synthesis was not impaired. In addition, the number of viable cells remained almost unchanged in the presence of 100 microM RXM. RXM induced growth inhibition at least partly by the formation of multinucleate cells. Both flowcytometric and morphological examination revealed that more than 40% of the RXM-treated cells were binucleate. These findings demonstrate that RXM is a potent new modulator of cell cycle progression in HL60 cells and suggest that the inhibition of cytokinesis by this drug may provide a new model for studying mitosis.

Bromodeoxyuridine↗
PubMed1995

Differences in the interleukin-2 (IL-2) receptor system in human and mouse: alpha chain is required for formation of the functional mouse IL-2 receptor.

Reconstitution with mouse interleukin-2 (IL-2) receptor subunits demonstrated that the mouse IL-2 receptor complex was different from the human complex in the alpha chain requirement for the functional mouse receptor complex. The heterotrimeric complex of the mouse exogenous alpha and beta chains and the endogenous gamma chain on mouse lymphoid BW5147 cells showed the ability to bind IL-2 with high affinity, resulting in IL-2-induced tyrosine phosphorylation of a cytosolic tyrosine kinase, JAK3, which is involved in IL-2-dependent signals. Exogenous introduction of the beta chain with the endogenous gamma chain, however, could neither confer appreciable IL-2 binding nor IL-2-induced signal transduction on BW5147 cells, unlike the human beta gamma heterodimer. Mouse spleen CD8+ cells, not having the alpha chain initially, showed IL-2-dependent cell proliferation only when expression of the alpha chain was induced. Collectively, these results illustrate that the functional mouse IL-2 receptor complex necessarily includes the alpha chain, and that the regulation of CD8+ T cell growth during immune reaction depends upon alpha chain expression.

Animals↗
PubMed1995

Interaction of family history of breast cancer and dietary antioxidants with breast cancer risk (New York, United States).

We sought to determine if specific dietary antioxidants may be particularly effective in reducing breast cancer risk for women reporting family history (FH) of breast cancer in a first-degree relative. Interviews regarding usual diet, health, and family histories were conducted with 262 premenopausal and 371 postmenopausal women with incident, primary breast cancer from western New York (United States). These women were frequency-matched by age and county of residence with community controls. Among premenopausal women, there was a significant interaction between FH and alpha-tocopherol; alpha-tocopherol was associated with significantly decreased risk among FH+ women (adjusted fourth-quartile odds ratio [OR] = 0.01, 95 percent confidence interval [CI] = 0.0-0.3). This association was much weaker for FH- women [OR = 0.7, CI = 0.4-1.2]. For FH- women, a significant inverse association was observed between beta-carotene and premenopausal breast-cancer risk (OR = 0.4, CI = 0.3-0.5), but not for FH+ women (OR = 0.5, CI = 0.1-4.0). Similar relationships, although not as strong, were noted among postmenopausal women. Although limited by small numbers, these results suggest that biologic mechanisms of tumorigenesis may differ in FH+ and FH- women, and that alpha-tocopherol may be a potential chemopreventive agent for women with a family history of breast cancer, particularly premenopausal women.

Adult↗
PubMed1995

Lifetime alcohol consumption and risk of breast cancer.

The relation of lifetime alcohol intake to risk of breast cancer in pre- and postmenopausal women was examined in a case-control study in western New York. Cases with incident primary histologically confirmed breast cancer diagnosed during the period 1986-1991 (n = 740) and controls, frequency age-matched women drawn from New York state driver's license records (age < 65 yrs) and from records of the Health Care Finance Administration (age > or = 65 yrs, n = 810), were interviewed regarding intake of wine, beer, and hard liquor 2, 10, and 20 years ago and at 16 years of age. Although women in this study had generally low intakes of alcohol, there was little evidence of increased risk of breast cancer with intake of alcohol at any of the time periods or with an index of total lifetime intake. There was a weak indication of an increase in risk with beer for intakes of at least one drink per day. This risk was evident for 2, 10, and 20 years ago but not at 16 years of age. In this group with relatively low intakes of alcohol, evidence was weak for an association of increased risk of breast cancer with intake of alcohol, with the possible exception of a weak association with beer intake.

Adolescent↗
PubMed1995

Effects of nicorandil on the recovery of reflex potentials after spinal cord ischaemia in cats.

1. The pathophysiological significance of ATP-sensitive K+ (KATP) channels in the central nervous system is not fully understood. In this study the effects of nicorandil (a hybrid vasodilator having a dual mechanism of action as a K+ channel opener and a nitrate) on the recovery of the spinal cord reflex potentials after spinal cord ischaemia were examined and compared with those of pinacidil and nitroprusside in anaesthetized spinal cats. 2. Spinal cord ischaemia was produced by occlusion of the thoracic aorta and the bilateral internal mammary arteries for 10 min. Regional blood flow in the spinal cord was continuously measured with a laser-Doppler flow meter. The monosynaptic (MSR) and polysynaptic reflex (PSR) potentials, elicited by electrical stimulation of the tibial nerve, were recorded from the lumbo-sacral ventral root. The recovery process of spinal reflex potentials was reproducible when the occlusion was repeated twice at an interval of 120 min. 3. Pretreatment with nicorandil (30-100 micrograms kg-1) accelerated the recovery of PSR potentials after spinal cord ischaemia. Such an accelerating effect on the recovery of PSR potentials was also shared by pinacidil (100 micrograms kg-1), another K+ channel opener. In addition, the accelerating effect of nicorandil (100 micrograms kg-1) on the recovery of PSR potentials was abolished by co-administration of glibenclamide (3 mg kg-1), a sulphonylurea KATP channel blocker. Nitroprusside (8 micrograms kg-1min-1) retarded rather than improved the recovery of PSR potentials after spinal cord ischaemia. All of these drugs failed to improve the spinal cord blood flow during ischaemia and reperfusion. 4 These results suggest that nicorandil promotes the recovery of polysynaptic reflex potentials after spinal cord ischaemia by opening the KATP channels of neurones rather than by increasing local bloodflow. K+ channel openers may exert a salutary effect on the functional recovery of the ischaemic spinal cord.

Animals↗
PubMed1995

[Usefulness of endotoxin-specific limulus test for the measurement of endotoxin in cerebrospinal fluid in diagnosis of bacterial meningitis].

Using a new endotoxin-specific chromogneic limulus assay (Endoscopy test), endotoxin concentrations were measured in 93 specimens of cerebrospinal fluid (CSF) from 66 pediatric patients. Eighteen patients were diagnosed as having menigitios. Of these, 6 cases (group A) with gram-negative meningitis proven by culture had high CSF endotoxin concentrations of 115.3, (82-133) (median, range) pg/ml. Ten cases (group B) with gram-positive or aseptic meningitis had endotoxin concentrations of 2.15 (0.1-3.6) pg ml. Other 2 cases with bacterial meningitis (group C), in whom no pathogen was detected, had CSF endotoxin concentrations of more than 100 pg/ml. Four cases with encephalitis (group D) and 45 cases with non-meningitis or non- encephalitis (group E), had CSF endotoxin concentrations of less than 5 pg/ml. Despite a negative culture after antibiotic treatment in group A patients, endotoxin was cleared slowly from the CSF. A clearing of endotoxin from CSF was followed by alleviation of fever with a more gradual decline in CRP values. In 2 cases of group C, the negative bacterial culture appeared to be attributable to the previous treatment with antibiotics. However, these patients had high CSF endotoxin levels, indicating gram negative bacterial meningitis. In 17 CSF specimens from 5 patients of group A, in whom Haemophilus influenzae was detected on admission, an additional a latex agglutination test for the detection of H. influenzae polysaccharide antigen was performed. Only 3 specimens from 3 patients with CSF endotoxin concentrations of more than 80 pg/ml had a positive agglutination test. These results suggest that quantitation of endotoxin concentrations is useful for the diagnosis of gram-negative meningitis. And also, the clearance of endotoxin from CSF during treatment appears to be useful in determining the timing of when antibiotic should be stopped.

Adolescent↗
PubMed1995

Solitary pulmonary nodule: preliminary study of evaluation with incremental dynamic CT.

PURPOSE: To use incremental dynamic computed tomography (CT) to evaluate solitary pulmonary nodules (SPNs). MATERIALS AND METHODS: Thirty-two adult patients with SPNs less than 3 cm in diameter had 18 primary lung cancers, 10 tuberculomas, and four hamartomas. The CT numbers of the inner area of the nodule were calculated before and 30 seconds, 2 minutes, and 5 minutes after administration of contrast material. RESULTS: All lung cancers and one of four hamartomas showed significantly greater enhancement (P < .0001) than benign SPNs, which did not show enhancement (except for one hamartoma). All lung cancers and one of four hamartomas showed complete enhancement, one hamartoma showed peripheral enhancement, two hamartomas and eight of 10 tuberculomas showed capsular enhancement, and two tuberculomas showed no enhancement. CONCLUSION: Maximum attenuation of 20-60 HU appears to be a good predictor of malignancy.

Adult↗