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Biomedical subjects

A Ishida

Publications and source records attributed to A Ishida.

At least 91 records · Page 5Linked to original sources
PubMed1999

Treatment of advanced myelodysplastic syndrome with a regimen including recombinant human granulocyte colony-stimulating factor preceding allogeneic bone marrow transplantation.

We treated 13 patients with morphologically advanced myelodysplastic syndrome using cytosine arabinoside and total body irradiation, followed by allogeneic marrow transplantation from HLA-identical sibling donors. Granulocyte colony-stimulating factor (G-CSF) was added to the preparative regimen to selectively increase chemosensitivity of leukaemic cells and to improve transplant outcome. No regimen-related deaths occurred, and no side-effects related to the addition of G-CSF were observed except for transient mild bone pain. At a median follow-up time of 39 months the projected 5-year disease-free survival and 5-year overall survival were 67.7% and 75.5%, respectively, with only one case showing cytogenetic relapse. The preparative regimen including G-CSF is feasible, and preliminary results seem to be encouraging. However, a larger trial is clearly warranted to evaluate its efficacy.

Adolescent↗
PubMed1999

Juxtaglomerular cell tumor with retroperitoneal fibrosis and secondary immune-complex glomerulonephritis: a possible contribution of the renin angiotensin system to renal fibrosis.

We present a case of a 25-year-old woman with a renin-secreting juxtaglomerular cell tumor, retroperitoneal fibrosis associated with glomerular hypertrophy, glomerulonephritis, and marked tubulointerstitial alterations. Myofibroblasts, as shown by positive immunostaining for alpha-smooth muscle actin, were found along with transforming growth factor-beta (TGF-beta) in the interstitium of the tumor-free kidney. Regarding the pathogenesis of renal fibrosis and glomerular hypertrophy, this case may provide evidence not only experimentally but also clinically that the renin-angiotensin system plays an important role because angiotensin II is known to induce renal fibrosis associated with increased TGF-beta and the appearance of myofibroblasts.

Actins↗
PubMed1999

Molecular cloning of Ca2+/calmodulin-dependent protein kinase phosphatase.

Calmodulin-dependent protein kinase (CaM-kinase) phosphatase dephosphorylates and concomitantly deactivates CaM-kinase II activated upon autophosphorylation, and CaM-kinases IV and I activated upon phosphorylation by CaM-kinase kinase [Ishida, I., Okuno, S., Kitani, T., Kameshita, I., and Fujisawa, H. (1998) Biochem. Biophys. Res. Commun. 253, 159-163], suggesting that CaM-kinase phosphatase plays important roles in the function of Ca2+ in the cell, because the three multifunctional CaM-kinases (CaM-kinases I, II, and IV) are thought to be the key enzymes in the Ca2+-signaling system. In the present study, cDNA for CaM-kinase phosphatase was cloned from a rat brain cDNA library. The coded protein consisted of 450 amino acids with a molecular weight of 49, 165. Western blot analysis showed the ubiquitous tissue distribution of CaM-kinase phosphatase. Immunocytochemical analysis revealed that CaM-kinase phosphatase is evenly distributed outside the nucleus in a cell.

Amino Acid Sequence↗
PubMed1999

Detection of a variety of Ser/Thr protein kinases using a synthetic peptide with multiple phosphorylation sites.

A novel peptide with multiple phosphorylation sites, which we designated as multide, was developed to detect a wide variety of protein kinases in crude cell extracts. Multide, KKRKSSLRRWSPLTPRQMSFDC, has been designed to contain consensus sequences for various Ser/Thr protein kinases including cAMP-dependent protein kinase, protein kinase C, MAP kinases, and Ca(2+)/calmodulin-dependent protein kinases in a single peptide. In-gel protein kinase assay using multide was found to be very useful for analyzing the activities of protein kinases that are altered in response to various extracellular stimuli. The substrate specificities of the protein kinases thus detected were further determined by using five multide analogs with different phosphorylation sites.

Amino Acid Sequence↗
PubMed1999

A simple radiographic measurement method for polyethylene wear in total knee arthroplasty.

This study describes a new method for evaluating polyethylene wear in total knee arthroplasty. Since the amount of wear is dependent on a number of variables such as the weight and activity of the patient, it should be estimated based on in vivo measurements. We used a computer vision technique called three-dimensional/two-dimensional (3-D/2-D) matching to perform in vivo assessment using a single-plane radiograph. Using the 3-D/2-D matching algorithm we estimated the 3-D position and orientation of each knee implant and then measured the femorotibial distance, which is defined as the shortest perpendicular distance from the tibial tray to the femoral component. The accuracy of the proposed 3-D/2-D matching method was determined by in vitro investigations. The worst errors in in-plane/out-of-plane translations and rotations were 0.20/1.95 mm and 0.17/0.29 degrees, respectively. The root-mean-square error in femorotibial distance measurements using real polyethylene inserts was 0.04 mm. Results of in vivo femorotibial distance measurements are also described.

Humans↗
PubMed1999

Characteristics of visual feedback in postural control during standing.

In the present study, the visual feedback system in postural control was investigated. To suppress the vestibular and proprioceptive feedback paths, a subject stood on a force-measuring plate with a fixed back support. Because the subject's body was immovable under these conditions, the subject controlled a computer model which simulated body dynamics. Information on the sway angle of the model was fed visually. Under this condition, frequency response functions for the ankle moment in response to the sway angle were calculated. The experimental results suggest that the visual feedback system contains a large time delay and, consequently, the visual system does not by itself allow a subject to maintain an upright posture. Index Terms- Feedback control, frequency characteristics, identification, posture, visual sensory feedback.

Adult↗
PubMed1999

Tumor suppressor p53 but not cGMP mediates NO-induced expression of p21(Waf1/Cip1/Sdi1) in vascular smooth muscle cells.

Cyclin-dependent kinase inhibitor p21(Waf1/Cip1/Sdi1) has been suggested to be involved in the antiproliferative effect of nitric oxide (NO) in vascular smooth muscle cells (VSMCs). To elucidate the mechanism underlying NO-induced p21 expression, we investigated the roles of tumor suppressor p53 and the guanylate cyclase-cGMP pathway. The induction of p21 by the NO donor S-nitroso-N-acetylpenicillamine (SNAP) seemed to be due to transactivation because SNAP elevated the activity of p21 promoter but did not stabilize p21 mRNA and protein. Because SNAP did not stimulate the deletion mutant of p21 promoter that lacked p53 binding sites, we tested the involvement of p53. The expression level of p53 was down-regulated after mitogenic stimulation, whereas it was sustained in the presence of SNAP. SNAP markedly stimulated DNA binding activity of p53. Furthermore, SNAP failed to induce p21 in VSMCs obtained from p53-knock out mice and in A431 cells that contained mutated p53. The antiproliferative effect of SNAP also was attenuated in these cells. NO stimulates guanylate cyclase and its product cGMP has been shown to inhibit VSMC proliferation. However, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a guanylate cyclase inhibitor, did not prevent SNAP-induced p21 expression. 8-Bromo-cGMP, 3-isobutyl-1-methylxanthine, and their combination did not induce p21. Although 8-bromo-cGMP had a small antiproliferative effect, the elevation of cGMP concentration induced by SNAP was little throughout the G(1) phase. The antiproliferative effect of SNAP was not attenuated by Rp-8-bromoguanosine-3',5'-monophosphorothioate, an inhibitor of cGMP-dependent protein kinase. These results suggested that NO induces p21 through a p53-dependent but cGMP-independent pathway.

Cell Division↗
PubMed1999

Regulation of growth hormone-releasing hormone receptor messenger ribonucleic acid expression by glucocorticoids in MtT-S cells and in the pituitary gland of fetal rats.

Regulation of GH-releasing hormone receptor (GHRH-R) messenger RNA (mRNA) expression was studied, with the ribonuclease protection assay, in the fetal rat pituitary gland and in MtT-S clonal cells. GHRH-R mRNA was first detected on embryonic day (E)19 and increased rapidly thereafter, to reach a maximum at E21. Incubation of E17 or E18 pituitaries with 50 nM dexamethasone (DEX), a synthetic glucocorticoid, induced GHRH-R mRNA expression, suggesting that glucocorticoids play a pivotal role in the developmental expression of this mRNA. In E19 pituitaries, 24 h treatment with DEX increased GHRH-R mRNA by 60%, and GH mRNA by 76%, but did not affect pit-1 mRNA level, suggesting that the effect of DEX is specific for expressions of GH mRNA and GHRH-R mRNA. The accumulation of GHRH-R mRNA by DEX was time dependent, and it was slightly enhanced by the protein synthesis inhibitor, puromycin (100 microM). In MtT-S cells (a pituitary cell line established from an estrogen-induced tumor), DEX induced GHRH-R mRNA expression within 2 h in a dose-dependent manner. This induction was augmented by puromycin (100 microM) or cycloheximide (3.5 microM). However, the RNA synthesis inhibitor Actinomycin D (1 microM) completely inhibited GHRH-R mRNA accumulation in response to either DEX or DEX plus puromycin, suggesting that glucocorticoids induce GHRH-R mRNA mainly through stimulation of mRNA transcription. These results suggest: that GHRH-R mRNA accumulation in the fetal pituitary gland of rats normally occurs at E19, probably because of the direct action of glucocorticoids on the pituitary gland, to stimulate GHRH-R mRNA transcription; and that the expression of glucocorticoid receptors is an important event in GH cell development in rats. Accordingly, immunocytochemical results suggest an increase in glucocorticoid receptors in immature GH cells between E17 and E18. The present results also imply that MtT-S cells may be a good model in which to further study the molecular mechanisms of the regulation of GHRH-R gene expression.

Animals↗
PubMed1999

[Proliferation inhibition of glioma cells by vitamin K2].

The antitumor effects of vitamin K2 were studied using three glioma cell lines: C6 (rat glioma cell), RBR17T and T98G (human glioma cell). The antitumor effects were estimated by count assay. The results was that vitamin K2 induced growth inhibition in a dose-dependent manner. The RBR 17T cells exposed to vitamin K2 for 72 hours resulted in oligonucleosomal DNA fragmentation and formed a ladder on agarose gel electrophoresis. Furthermore, the RBR17T cells exposed to vitamin K2 for 24 hours were significantly accumulated in the G0G1 phase of the cell cycle. Those results suggested that vitamin K2 can inhibit the proliferation of cells through the induction of cell cycle arrest and apoptosis for tumor cells. The combined treatment of vitamin K2 with ACNU or 5-FU or INF-beta or 1,25-dihydroxyvitamin D3 enhanced growth inhibition significantly. In conclusion, vitamin K2 can be a useful drug for the treatment of glioma.

Animals↗
PubMed1999

Clinical significance of the F wave area in diabetic polyneuropathy.

OBJECTIVE: To investigate the electrophysiological significance of the abnormal F wave are (Farea) and its ratio (F/Marea) (%) to the corresponding M wave area (Marea) in patients with diabetic polyneuropathy (DP). MATERIALS AND METHODS: For tibial and peroneal nerves, the F/Marea and other F wave parameters (duration [Fdur], minimum latency [Fmin], amplitude [Famp]) were compared in 34 patients and age-matched controls. RESULTS: For controls, the Farea correlated with the Marea, but this was not found for DP patients. The peroneal F/Marea for DP patients was significantly larger than that for controls. For the both nerves, however, the F/Marea for DP patients was larger in nerves with a decreased Marea than those in nerves with a normal Marea and in the controls. An increased F/Marea was accompanied by prolonged Fdur. A decreased F/Marea was uncommon. The incidence of abnormal F/Marea was somewhat larger than that of abnormal F/Mamp, but smaller than the values for MCV and Fmin. CONCLUSIONS: The relationship between Farea and the Marea for DP patients differed from that of controls. An increased F/Marea was considered to reflect a denervation-reinnervation process or some central modification in firing of the anterior horn cells. Whereas amplitude of the F wave also reflect these electrophysiological conditions, the F/Marea is a little more sensitive than F/Mamp in detecting the abnormality.

Diabetic Neuropathies↗
PubMed1998

Thrombopoietin induces association of Crkl with STAT5 but not STAT3 in human platelets.

Crkl, a 39-kD SH2, SH3 domain-containing adapter protein, is constitutively tyrosine phosphorylated in hematopoietic cells from chronic myelogenous leukemia (CML) patients. We recently reported that thrombopoietin induces tyrosine phosphorylation of Crkl in normal platelets. In this study, we demonstrate that thrombopoietin induces association of Crkl with a tyrosine phosphorylated 95- to 100-kD protein in platelets and in UT7/TPO cells, a thrombopoietin-dependent megakaryocytic cell line. With specific antibodies against STAT5, we demonstrate that the 95- to 100-kD protein in Crkl immunoprecipitates is STAT5. This coimmunoprecipitation was specific in that Crkl immunoprecipitates do not contain STAT3, although STAT3 becomes tyrosine phosphorylated in thrombopoietin-stimulated platelets. The coimmunoprecipitaion of Crkl with STAT5 was inhibited by the immunizing peptide for Crkl antisera or phenyl phosphate (20 mmol/L). After denaturing of Crkl immunoprecipitates, Crkl was still immunoprecipitated by Crkl antisera. However, coimmunoprecipitation of STAT5 was not observed. Coincident with STAT5 tyrosine phosphorylation, thrombopoietin induces activation of STAT5 DNA-binding activity as demonstrated by electrophoretic mobility shift assays (EMSA). Using a beta-casein promoter STAT5 binding site as a probe, we have also demonstrated that Crkl antisera supershift the STAT5-DNA complex, suggesting that Crkl is a component of the complex in the nucleus. Furthermore, interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), and erythropoietin also induce Crkl-STAT5 complex formation in responding cells in a stimulation-dependent manner. In vitro, glutathione S-transferase (GST)-Crkl bound to STAT5 inducibly through its SH2 domain. These results indicate that thrombopoietin, IL-3, GM-CSF, and erythropoietin commonly induce association of STAT5 and Crkl and that the complex translocates to the nucleus and binds to DNA. Interestingly, such association between STAT5 and Crkl was not observed in cytokine-stimulated murine cells, suggesting an intriguing possibility that components of the human STAT5-DNA complex may be different from those of the murine counterpart.

Acute-Phase Proteins↗
PubMed1998

Regulation of multifunctional Ca2+/calmodulin-dependent protein kinases by Ca2+/calmodulin-dependent protein kinase phosphatase.

We have recently reported a novel protein phosphatase which dephosphorylates and thereby deactivates Ca2+/calmodulin-dependent protein kinase II (CaMKII) activated through autophosphorylation (Ishida, A., Kameshita, I., and Fujisawa, H. (1998) J. Biol. Chem. 273, 1904-1910). In the present study, we show that this protein phosphatase also catalyzed dephosphorylation of Ca2+/calmodulin-dependent protein kinases I (CaMKI) and IV (CaMKIV) which had been phosphorylated and activated by Ca2+/calmodulin-dependent protein kinase kinase alpha, resulting in reversible deactivation of the enzymes. The fairly high degree of the substrate specificity of this protein phosphatase suggests that the physiological significance of the phosphatase may be the regulation of the three multifunctional Ca2+/calmodulin-dependent protein kinases, CaMKI, CaMKII, and CaMKIV, which are the key enzymes in a Ca(2+)-signaling system in the cell.

Animals↗
PubMed1998

Evidence for circulating bone marrow-derived endothelial cells.

It has been proposed that hematopoietic and endothelial cells are derived from a common cell, the hemangioblast. In this study, we demonstrate that a subset of CD34(+) cells have the capacity to differentiate into endothelial cells in vitro in the presence of basic fibroblast growth factor, insulin-like growth factor-1, and vascular endothelial growth factor. These differentiated endothelial cells are CD34(+), stain for von Willebrand factor (vWF), and incorporate acetylated low-density lipoprotein (LDL). This suggests the possible existence of a bone marrow-derived precursor endothelial cell. To demonstrate this phenomenon in vivo, we used a canine bone marrow transplantation model, in which the marrow cells from the donor and recipient are genetically distinct. Between 6 to 8 months after transplantation, a Dacron graft, made impervious to prevent capillary ingrowth from the surrounding perigraft tissue, was implanted in the descending thoracic aorta. After 12 weeks, the graft was retrieved, and cells with endothelial morphology were identified by silver nitrate staining. Using the di(CA)n and tetranucleotide (GAAA)n repeat polymorphisms to distinguish between the donor and recipient DNA, we observed that only donor alleles were detected in DNA from positively stained cells on the impervious Dacron graft. These results strongly suggest that a subset of CD34+ cells localized in the bone marrow can be mobilized to the peripheral circulation and can colonize endothelial flow surfaces of vascular prostheses.

Animals↗
PubMed1998

Abnormal left ventricular diastolic filling patterns in small-for-gestational-age infants.

Doppler transmitral flow velocity patterns in assessing left ventricular diastolic function in small-for-gestational-age infants have been poorly understood. The purpose of this study is to examine Doppler filling patterns in small-for-gestational-age infants (n = 13) and to compare them with those in age-matched appropriate-for-gestational-age infants (n = 29). We measured peak flow velocities of early diastole (peak E wave) and atrial contraction (peak A wave), ratio of peak E wave to peak A wave (peak E/A wave), velocity time integrals of E wave (VTIE wave) and A wave (VTIA wave), ratio of VTIE wave to VTIA wave (VTIE/A wave), first third filling fraction, peak filling rate normalized to stroke volume, and deceleration time. Mean gestational age and heart rate did not show a significant difference between the appropriate- and the small-for-gestational-age infants. The mean birth weight in the small-for-gestational-age infants was significantly lower than that in the appropriate-for-gestational-age infants (802+/-220 vs. 1184+/-260 g, P<0.01). In the small-for-gestational-age infants, the peak E wave, peak A wave, peak E/A wave,VTIE wave, first third filling fraction, and peak filling rate normalized to stroke volume were significantly lower than those in the age-matched appropriate-for-gestational-age infants (21.9+/-6.7 vs. 32.2+/-6.9 cm/s, 26.5+/-6.2 vs. 34.5+/-6.2 cm/s, 0.82+/-0.15 vs. 0.93+/-0.14, 1.88+/-0.45 vs. 2.39+/-0.51 cm, 0.36+/-0.04 vs. 0.41+/-0.04, 5.86+/-0.75 vs. 7.11+/-0.63/s, P<0.05, respectively). In the small and appropriate for gestational age infants, peak E wave, VTIE wave, and peak E/A increased significantly with increasing body weight. In the small-for-gestational-age infants, the slopes of regression lines between body weights and peak E wave and VTIE wave were significantly lower than those in the appropriate for gestational age infants, suggesting a significant reduction in E wave even when considering a difference in their body weight. This study suggests that the significant decreases in the early diastolic filling in the small-for-gestational-age infants may be related to the reduced left ventricular diastolic function.

Blood Flow Velocity↗
PubMed1998

Critical amino acid residues of AIP, a highly specific inhibitory peptide of calmodulin-dependent protein kinase II.

The importance of the individual amino acid residues of AIP (KKALRRQEAVDAL), a highly specific inhibitor of calmodulin-dependent protein kinase II (CaMKII), was studied. Replacement of Arg6, Gln7, or Ala9 by other amino acid residues produced a marked increase in the IC50 value. Leu4 and Val10 were also sensitive to replacement, but some hydrophobic amino acids could substitute for these residues. Although replacement of Ala3, Glu8, Ala12, and Leu13 by other residues produced no significant increase in the IC50, the substitution of Lys for Ala3 decreased the IC50. An AIP analog (KKKLRRQEAFDAY), in which Ala3 and Val10 were replaced with Lys and Phe, respectively, showed an IC50 value as low as 4 nM, suggesting that it is a useful tool for studying the physiological roles of CaMKII.

Animals↗
PubMed1998

Evidence for axial coordination of 5,6-dimethylbenzimidazole to the cobalt atom of adenosylcobalamin bound to diol dehydratase.

It was demonstrated by electron paramagnetic resonance (EPR) spectroscopy that organic radical intermediates disappeared and cob(II)alamin accumulated upon suicide inactivation of diol dehydratase by 2-methyl-1,2-propanediol. The resulting EPR spectra showed that the eight hyperfine lines due to the divalent cobalt atom of cob(II)alamin further split into triplets by the superhyperfine coupling to the 14N nucleus. Essentially the same superhyperfine splitting of the octet into triplets was observed with [14N]- and [15N]apoenzyme. When the adenosyl form of [14N2]- and [15N2]imidazolyl analogues of the coenzyme [Toraya, T., and Ishida, A. (1991) J. Biol. Chem. 266, 5430-5437] was used with unlabeled apoenzyme, the octet showed superhyperfine splitting into triplets and doublets, respectively. Therefore, it was concluded that cobalamin is bound to this enzyme with 5,6-dimethylbenzimidazole coordinating to the cobalt atom. This conclusion is consistent with the fact that the consensus sequence forming part of a cobalamin-binding motif, conserved in methionine synthase and some of the other cobalamin enzymes, was not found in the deduced amino acid sequences of the subunits of diol dehydratase. Adenosylcobinamide methyl phosphate, a coenzyme analogue lacking the nucleotide moiety, underwent cleavage of the cobalt-carbon bond upon binding to the enzyme in the presence of substrate, forming a cob(II)inamide derivative without nitrogenous base coordination, as judged by EPR and optical spectroscopy. Therefore, this analogue may be a useful probe for determining whether the replacement of the 5, 6-dimethylbenzimidazole ligand by a histidine residue takes place upon binding of cobalamin to proteins.

Benzimidazoles↗