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Biomedical subjects

K Okada

Publications and source records attributed to K Okada.

At least 667 records · Page 37Linked to original sources

[Expression of nm23/NDP kinase and cancer metastasis].

The nm23 gene was originally identified by differential hybridization between low and highly metastatic murine melanoma lines. The nm23 protein is identical with NDP kinase and there are at least two isotypes in several mammalian species such as human, mice and rats. Reduced expression of nm23/NDP kinase gene has been reported of association with highly metastatic characteristics in several experimental tumors and in certain types of human cancer. Detailed mechanisms of nm23 molecules in metastasis suppression remain unknown. The nm23/NDP kinase appears to participate to multiple cellular functions such as differentiation, proliferation and development. In this article, we reviewed recent reports on nm23/NDP kinase.

Animals↗

[Serial changes of atrial natriuretic peptide and brain natriuretic peptide during cesarean section under spinal anesthesia].

Both atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are considered to play a role in regulation of body fluid volume and blood pressure. Serial changes of their plasma concentrations are known to reflect blood volume. In this study, we investigated the serial changes in maternal blood concentrations of ANP and BNP in those who underwent cesarean section under spinal anesthesia. Blood samples were obtained before anesthesia, before surgery, at the end of surgery, and on the next morning. Samples were also compared with those from normal pregnant women. Throughout the cesarean section, ANP did not show any significant changes, while BNP remained within normal ranges during anesthesia and increased on the next morning. We concluded that ANP and BNP were regulated differentially, and that BNP reflected blood volume significantly during and after spinal anesthesia.

Adult↗

[Treatment of localized prostate cancer: radical prostatectomy versus radiation therapy].

Between 1982 and 1990, 57 patients with prostate cancer (clinical stage T2-3) underwent pelvic lymphadenectomy at Fukui Medical School or Toyooka Public Hospital. The patients were subsequently treated either by radical prostatectomy (39 cases) or external radiation therapy (18 cases). The patients were between 56 and 85 years old (Mean 73). The outcome of the 47 patients without lymph node metastasis (prostatectomy 33, radiation 14) was examined. The 5-year disease-specific survival rate was 96% for the patients treated by prostatectomy and 93% for those treated by radiation. The 5-year progression-free survival rate for the prostatectomy group and radiation group was 94% and 41%, respectively (P = 0.004). The outcome of the 10 patients with lymph node metastasis (prostatectomy 6, radiation 4) was not satisfactory because of the high progression rate in the two groups (5-year progression-free survival, 22% in prostatectomy and 25% in radiation group). In the patients with no metastasized lymph nodes, we should choose radical prostatectomy, if our goal is to cure the patients.

Aged↗

[A case report of bypass grafting for coronary atherosclerosis with anomalous origin of the left coronary artery from the right coronary artery ostium-anterior subtype].

A 73-year-old female began to suffer from effort-induced chest pain and later disabling angina pectoris. Coronary angiographic evaluation disclosed that both the right and left coronary arteries originated from the right sinus of Valsalva. The dominant right coronary artery had a normal course with a 90% narrowing in the first segment. The left main trunk crossed anteriorly the pulmonary artery conus, thereafter dividing into the left anterior descending and circumflex coronary arteries with two 99% narrowings in the seventh and eleventh segment. She underwent bypass of the left anterior descending and right posterior descending coronary arteries with the left interthoracic artery, the right gastroepiploic artery, and saphenous vein graft on cardiopulmonary bypass support. The postoperative course was uncomplicated.

Aged↗

Procoagulant properties of intravenous staphylokinase versus tissue-type plasminogen activator.

The fibrin-specificity and procoagulant effects of recombinant staphylokinase (Sak42D) were compared with those of recombinant tissue-type plasminogen activator (rt-PA) in patients with acute myocardial infarction. Plasma samples were obtained at baseline and at 25 and 90 min, from 24 patients who were randomly assigned to a double bolus (15 mg each, 30 min apart) administration of Sak42D or to accelerated weight-adjusted rt-PA (maximum of 100 mg over 90 min). Baseline levels of fibrinopeptide A (FPA), prothrombin fragment 1 + 2 and thrombin-antithrombin III complex (TAT) were comparable in the Sak42D and rt-PA groups (p > or = 0.6). In patients treated with Sak42D, plasma levels of FPA, prothrombin fragment 1 + 2 and TAT did not markedly increase during treatment (p = 0.06, p = 0.4 and p = 0.03, respectively). In contrast, during administration of rt-PA the levels of FPA, prothrombin fragment 1 + 2 and TAT increased significantly over baseline (p = 0.003, p < 0.0001 and p = 0.001, respectively). As a result, the levels of all three procoagulant parameters were significantly lower during treatment with Sak42D as compared to rt-PA. Thus, FPA levels in the Sak42D group (median values) were 40 ng/ml at 25 min and 11 ng/ml at 90 min, as compared to 88 ng/ml and 50 ng/ml in the rt-PA group (p = 0.0007 and p = 0.009, respectively). Prothrombin fragment 1 + 2 levels in the Sak42D group were 1.3 nM at 25 min and 1.2 nM at 20 min, as compared to 11 nM and 5.3 nM in the rt-PA group (both p < 0.0001). TAT levels were 4.7 ng/ml at 25 min and 6.2 ng/ml at 90 min in the Sak42D group, with corresponding values of 16 ng/ml and 9.6 ng/ml in the rt-PA group (p = 0.02 and p = 0.03, respectively). In the patients treated with Sak42D, no significant systemic fibrinolytic activation was observed, as revealed by unaltered levels of clottable fibrinogen, plasminogen and alpha 2-antiplasmin up to 90 min after the start of therapy. In contrast, the corresponding residual levels at 90 min in patients treated with rt-PA decreased to (mean +/- SEM; n = 12) 62 +/- 6%, 45 +/- 5% and 52 +/- 10%, respectively (all p < or = 0.01 versus the Sak42D group). These data confirm the high degree of fibrin-specificity of Sak42D and demonstrate that this is associated with significantly less generation of procoagulant activity in plasma after intravenous administration in patients with acute myocardial infarction.

Fibrinolytic Agents↗

Thrombopoietin induces tyrosine phosphorylation and activation of mitogen-activated protein kinases in a human thrombopoietin-dependent cell line.

Thrombopoietin (TPO) is a cytokine which can support the proliferation and differentiation of megakaryocyte progenitor cells, and the maturation of megakaryocytes. We show here that mitogen-activated protein (MAP) kinases, Erk1 and Erk2, are involved in TPO signal transduction in the human TPO-dependent megakaryocytic cell line, UT-7/TPO. TPO induced tyrosine phosphorylation of Erk1 and Erk2 proteins in a dose and time-dependent manner. Moreover, the activation of MAP kinases was actually induced by TPO. These results suggest that MAP kinase activation is involved in the signalling pathway of TPO, as it is for other cytokines, one of which is erythropoietin.

Calcium-Calmodulin-Dependent Protein Kinases↗

Effects of hyper- and hypoglycemia on blood growth hormone level in free-feeding rats with anterolateral deafferentation of the medial basal hypothalamus.

In rats with anterolateral deafferentation of the medial basal hypothalamus, the growth hormone (GH) level in the blood showed irregular and small fluctuations instead of the usual high bursts and low trough level, and the baseline GH level was higher than that in sham-operated rats. Continuous infusion of a glucose solution to operated rats increased the baseline level, GH pulse and pulse amplitude. I.v. bolus injection of the glucose solution resulted in a significant but transient increase in GH level. Insulin-induced hypoglycemia decreased the blood GH level in operated rats more effectively than in sham-operated ones and that was prevented by simultaneous infusion of glucose. Since SS influence on GH secretion had been largely eliminated in rats with anterolateral deafferentation of the medial basal hypothalamus, it is highly unlikely that the effects of hyperglycemia or hypoglycemia on GH secretion were the consequence of altered SS secretion.

Animals↗

Use of the bidirectional Glenn procedure in the presence of forward flow from the ventricles to the pulmonary arteries.

BACKGROUND: Relative regression of the pulmonary arterial size has been reported after a conventional bidirectional Glenn procedure. Maintaining a supplemental pulmonary flow could be of surgical value unless the option also militates against the efficacy of the partial right heart bypass. METHODS AND RESULTS: Twenty-seven patients considered unsuitable for a Fontan-type procedure underwent a bidirectional Glenn procedure in the presence of forward flow from the ventricles to the pulmonary arteries, the flow being maintained through the pulmonary trunk in 22 or a systemic-to-pulmonary shunt in 5. There was one surgical death due to atrioventricular valvular regurgitation. Subsequently, 9 patients have successfully undergone a total cavopulmonary connection 2.6 +/- 1.9 years after the initial procedure. Preoperative and postoperative catheterizations revealed changes in arterial oxygen saturation (75 +/- 11% compared with 83 +/- 7%, P < .001) and end-diastolic volumes of the systemic ventricles (from 238 +/- 92% to 188 +/- 97% of the expected normal volume, P < .01), whereas no difference was detected in the mean cross-sectional area of the right and left pulmonary arteries compared with the expected normal value for the right pulmonary artery (from 76 +/- 21% to 81 +/- 20%) or in the ventricular ejection fraction (from 53 +/- 8% to 50 +/- 14%). The relative regression or growth of the pulmonary arterial size was statistically related to the size of the channel for forward flow. CONCLUSIONS: Maintenance of forward flow from the ventricle provides a feasible means, when performing a bidirectional Glenn procedure, of protecting against regression of pulmonary arterial size as well as off-loading the ventricles and improving arterial oxygen saturation.

Adolescent↗

Developmental and tissue-specific regulation of the gene for the wheat basic/leucine zipper protein HBP-1a(17) in transgenic Arabidopsis plants.

Wheat basic/leucine zipper protein HBP-1a(17) binds in vitro specifically to ACGT motif-containing cis-acting elements, such as the type I element of plant histone promoters and the G-box of hormone- and light-inducible promoters. To address the in vivo function of HBP-1a(17), we isolated and structurally analyzed the HBP-1a(17) gene and examined its expression in transgenic Arabidopsis plants. The HBP-1a(17) gene is composed of 14 exons; the basic region and leucine zipper are encoded by separate small exons, as is the case for other bZIP protein genes. The G-box of the HBP-1a(17) promoter bound specifically to HBP-1a(17) and its related HBP-1a isoforms, suggesting that the HBP-1a(17) gene may be autoregulated, although the binding affinity of these proteins in vitro is very low. In Arabidopsis plants, activation of the HBP-1a(17) promoter was highly restricted to photosynthetically active mesophyll, and guard cells and vascular bundles of vegetative leaves. Etiolation of transgenic plants resulted in inhibition of expression of the HBP-1a(17) promoter. Indeed, the HBP-1a(17) promoter contains several sequence elements homologous to cis-acting elements conserved in light-inducible promoters. It is, therefore, assumed that the HBP-1a(17) gene is light regulated and that HBP-1a(17) is involved in light-responsive gene transcription via the G-box.

Amino Acid Sequence↗

Establishment of canine pulmonary hypertension with dehydromonocrotaline. Importance of larger animal model for lung transplantation.

Single lung isografting in rats with pulmonary hypertension has been reported. However, it is hard to evaluate cardiopulmonary hemodynamics accurately or to use circulatory assists during procedures using rats. Therefore, we tried to establish a model of pulmonary hypertension in the beagle. Twenty young beagles were randomized into 3 groups. An injection of dehydromonocrotaline of 1.5 mg/kg (group 1, n = 7), 3.0 mg/kg (group 2, n = 10), or 4.5 mg/kg (group 3, n = 3) was performed via the right atrium. Two dogs in group 2 and all the dogs in group 3 died of acute pulmonary edema. During the 8 weeks after injection, the systolic pulmonary arterial pressure and pulmonary vascular resistance index increased significantly in group 2 from 21 +/- 2 to 56 +/- 9 mmHg and from 106 +/- 39 to 826 +/- 176 dynes.sec.cm-5.m2, respectively (P < 0.01). The changes in group 1 were less pronounced. The dogs in group 2 also had a rise in their plasma endothelin-1. Pathologic analysis revealed thickening of the media in small pulmonary arteries and hypertrophy of the right ventricular myocardium. Our data indicate that beagles treated with 3.0 mg/kg dehydromonocrotaline produced a unique, relatively noninvasive model of pulmonary hypertension. In the model, right ventricular failure prevented us from clamping one pulmonary artery. These relatively large animals with pulmonary hypertension will be valuable for further studies of lung transplantation.

Animals↗

Role of endothelin-1 in beagles with dehydromonocrotaline-induced pulmonary hypertension.

BACKGROUND: Although plasma levels of endothelin-1 (ET-1) increase in patients with pulmonary hypertension (PH), its role in PH is unknown. We investigated the contribution of endogenous ET-1 to cardiopulmonary changes in beagles with dehydromonocrotaline (DMCT)-induced PH. METHODS AND RESULTS: Eight 3-month-old beagles were given a single injection of 3 mg/kg DMCT via the right atrium. During the 8 weeks after injection, the mean pulmonary arterial pressure (PAP) and plasma ET-1 level increased significantly from 11.6 +/- 2.3 to 35.9 +/- 7.1 mm Hg and from 1.24 +/- 0.25 to 3.25 +/- 0.94 pg/mL, respectively. In controls, ET-1 infusion elevated the systemic arterial pressure (SAP) but did not alter PAP. In PH beagles, ET-1 infusion increased SAP, which was attenuated by FR139317 (an endothelin type [ET] A receptor antagonist), and produced a dose-dependent decrease in PAP, which was attenuated by RES-701-1 (an ETB receptor antagonist). In PH beagles, FR139317 infusion decreased PAP, and RES-701-1 infusion increased PAP. Sarafotoxin S6c (an ETB agonist) infusion decreased PAP in PH beagles. CONCLUSIONS: These results suggest that endogenous ET-1 is elevated in PH disease and may mitigate PH by acting on ETB receptors.

Animals↗

Two isotypes of murine nm23/nucleoside diphosphate kinase, nm23-M1 and nm23-M2, are involved in metastatic suppression of a murine melanoma line.

A series of sublines of a murine melanoma B16 of C57BL/6 origin were established and examined regarding their metastatic capacity and expression of nm23. The number of pulmonary metastases developed by these sublines was inversely correlated with the expression of two isotypes of nm23, nm23-M1 and nm23-M2. The cDNAs of nm23-M1, nm23-M2, and a combination of both were transfected into the highly metastatic melanoma subline FE7, with low nm23 expression. FE7 transfectants of any of these cDNAs expressed transfected genes, and their metastatic capacity was suppressed when compared with parental FE7 or FE7 transfected with a control neo gene. These cell lines, however, did not change in terms of in vitro growth in the presence of 3 or 10% fetal bovine serum and in vivo growth when injected s.c. into C57BL/6-nu/nu mice. Similar experiments were also performed using FE7 transfectants of human nm23 genes. Transfectants of nm23-H1, nm23-H2, and their combination did not present altered metastatic potential. These findings indicated that two murine isotypes of nm23 but not those of humans are intimately related with the suppression of metastasis in the murine body.

Animals↗

Identification of a new bovine MHC class II DRB allele by nucleotide sequencing and an analysis of phylogenetic relationships.

Three overlapping cDNA clones coding for the bovine major histocompatibility complex (MHC) class II DR beta chain were isolated. A clone NR1 encoded a primary translated product of 266 amino acids, 29 of which were deduced to form a signal peptide and 237 to form the mature polypeptide. The protein predicted from this cDNA appeared to have all the features expected of an expressed MHC class II molecule. Comparison of the sequences and construction of a phylogenetic tree revealed that NR1 represents a BoLA-DRB3 gene and not a BoLA-DRB1 or BoLA-DRB2 pseudogene. NR1 and ovine sequences exhibited the greatest overall similarity among sequences from various mammalian species, followed by the equivalent human sequences. Indeed, the bovine allele was more closely related to certain ovine alleles than to other bovine alleles. A large number of replacement substitutions were identified when beta 1 domains encoded by NR1 and each of the 36 distinct BoLA-DRB3 alleles were compared, and most of the allelic variations were found in regions that are commonly polymorphic in DRB sequences from different species and correspond to the predicted antigen-recognition site. Thus, the predicted structure of the unique NR1 allele for BoLA-DRB3 further confirms the overall conservation of the product of this locus, as previously established from studies in rodent and man.

Alleles↗

Effect of cyclic AMP on urokinase-type plasminogen activator receptor and fibrinolytic factors in a human osteoblast-like cell line.

We investigated the effect of cyclic AMP (cAMP) on the pericellular fibrinolytic system in NY cells. Dibutyryl cAMP (dbcAMP) or forskolin increased the level of urokinase-type plasminogen activator (u-PA) mRNA and enhanced the secretion of u-PA antigen into the conditioned medium. These agents also increased u-PA antigen on the cell surface. PA inhibitor-1 (PAI-1) antigen was inhibited by dbcAMP or forskolin. Butyrate had no effect on the production and secretion of u-PA and PAI-1. A binding assay of 125I-DFP-u-PA to NY cells revealed a single class of binding sites with a Kd of 3.85 nM and Bmax of 0.89.10(5) binding sites/cell. The Bmax was increased by dbcAMP (1 mM or 10 mM), forskolin (2 microM or 20 microM) of 1.0-, 1.4-, 1.2- and 1.8-fold, respectively. However, the Kd value was not changed. Furthermore, the level of mRNA for the u-PA receptor (u-PAR) was increased by these agents 1.2-, 1.7-, 1.8- and 2.5-fold, respectively. However, butyrate did not alter either the Bmax or the u-PAR mRNA level. These results indicated that the pericellular fibrinolytic activity induced by u-PA/u-PAR is modulated by cAMP in osteoblast-like cells.

Bucladesine↗