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Biomedical subjects

Y Onishi

Publications and source records attributed to Y Onishi.

At least 19 recordsLinked to original sources
PubMed2005

Lower incidence of Bronchiolitis obliterans in allogeneic hematopoietic stem cell transplantation with reduced-intensity conditioning compared with myeloablative conditioning.

Bronchiolitis obliterans (BO) is one of the most devastating complications after allogeneic stem cell transplantation (HSCT). However, its true pathogenesis is still to be elucidated. We conducted this study to find whether tissue damage due to high-dose chemo-radiotherapy is related to its pathogenesis. In all, 144 patients who received allogeneic HSCT between May 1999 and October 2001, and survived more than 80 days after transplant, were analyzed. Clinical course, pulmonary function tests, imaging studies including CT scan, and pathology results were reviewed. The overall incidence of BO was 9.7% (14/144). The cumulative incidence of BO at 2 years after transplant was 17% with myeloablative conditioning, and 2.3% with reduced intensity conditioning (P=0.024). Multivariate analysis showed that myeloablative conditioning was the only factor which affected the incidence of BO. Development of BO did not significantly affect the overall survival of patients. However, if they developed BO earlier than 200 days post transplant, the prognosis was significantly worse than if they developed it later than 200 days post transplant (P=0.003) or if they did not develop BO (P=0.002). Our results imply that tissue damage secondary to intensive chemo-radiotherapy may contribute to the pathogenesis of BO.

Adolescent↗
PubMed2004

Integration-plot test for peri-stimulus time histograms in human motor units.

A statistical test is proposed for peri-stimulus time histograms in human motor units for the case where a test stimulus is delivered at a constant interval after a previous discharge. This mathematically described test included the notion of the multiple comparison and thus achieved higher sensitivity than the previously proposed method. With regard to data acquisition, the interval from a sham stimulus to the next discharge was acquired as a control, and the total number of samples was set to be four times as large as that in the test situation to reduce the statistical scattering noise. A newly defined statistical object, the integration plot (timewise accumulation of the test histogram without control subtraction) was used for this statistical test. The integration plot had less noise than the cumulative sum (CUSUM) plot (1/square root(2) in theory) and thus represented the neural effect. To compare this integration-plot test with that of the CUSUM, a simulation experiment that compared two sample histograms (one of which had a faint structural change from 20 ms) was conducted. As a result, the present test succeeded in detecting the onset of the change point earlier (23 ms on average) than the CUSUM test (27 ms on average), and the detection probability was also higher (9 out of 10) than the CUSUM (6 out of 10). It was therefore confirmed experimentally that the present statistical test had higher sensitivity than that of the CUSUM proposed previously.

Adult↗
PubMed2004

Reduced-intensity stem cell transplantation from an HLA-identical sibling donor in patients with myeloid malignancies.

The purpose of this study was to evaluate the feasibility and efficacy of allogeneic hematopoietic stem cell transplantation with a reduced-intensity regimen (RIST) in patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). In all, 36 patients (median age 55 years) underwent RIST from an HLA-matched related donor between September 1999 and December 2002. The diagnoses included AML (n=14), leukemia evolving from MDS (n=10), and MDS (refractory anemia with excess blasts n=6, refractory anemia n=6). The RIST regimen consisted of purine analog (cladribine or fludarabine)/busulfan, with or without antithymocyte globulin. The regimen was well tolerated, and 34 patients achieved durable engraftment and most achieved remission after RIST. A total of 17 patients developed grade II-IV acute GVHD, and 27 developed chronic GVHD. Eight patients relapsed, and five of them received antithymocyte globulin (ATG) as part of the preparative regimen. A total of 12 patients died (four disease progression, six transplantation-related complications, and two others). Estimated 1-year disease-free survival (DFS) in low- and high-risk groups was 85 and 64%, respectively. We conclude that RIST can be performed safely in elderly patients with myeloid malignancies, and has therapeutic potential for those who fail conventional chemotherapy. In view of the significant association between GVHD or ATG and DFS, defined management of GVHD following RIST should become a major target of clinical research.

Adult↗
PubMed2001

Direct reduction of alcohols: highly chemoselective reducing system for secondary or tertiary alcohols using chlorodiphenylsilane with a catalytic amount of indium trichloride.

The direct reduction of alcohols using chlorodiphenylsilane as a hydride source in the presence of a catalytic amount of indium trichloride is described. Benzylic alcohols, secondary alcohols, and tertiary alcohols were effectively reduced to give the corresponding alkanes in high yields. A compound bearing both primary and secondary hydroxyl groups was reduced only at the secondary site to afford the primary alcohol after workup with Bu(4)NF. This system showed high chemoselectivity only for the hydroxyl group while not reducing other functional groups that are readily reduced by standard reducing systems. Thus alcohols bearing ester, chloro, bromo, or nitro groups, which are sensitive to LiAlH(4) or Zn/H(+), were selectively reduced only at the hydroxyl sites by the chlorodiphenylsilane/InCl(3) system. NMR studies revealed the reaction course. The hydrodiphenylsilyl ether is initially formed and then, with InCl(3) acting as a Lewis acid, forms an oxonium complex, which accelerates the desiloxylation with donation of the hydrogen to the carbon.

Journal Article↗
PubMed2001

Enhancer activity of HS2 of the human beta-LCR is modulated by distance from the key nucleosome.

A class of curved DNA appears universally in eukaryotic genomic DNA at an average distance of approximately 680 bp and shows nucleosome positioning activity by having high affinity for histone core particles in an orientation- and position-dependent manner. Here, we report that the enhancer activity at DNase I hypersensitive site 2 (HS2) of the human beta-globin locus control region (beta-LCR) can be modulated by the curved DNA located at a distance of two nucleosomes from HS2 and that the nucleosome at the curved DNA regulates nearby nucleosome phases as a key nucleosome. Erythroid-specific nucleosome phases which caused deviation of the NF-E2 (p18-p45 dimer) binding site from the nucleosome dyad axis were over-represented when the distance between the key nucleosome and HS2 exceeded 80 bp longer than the original length. At this state, enhancer activity was approximately 50% of that in the original construct, presumably due to reduced binding of transcription factors.

Base Sequence↗
PubMed2001

Palmitoylation of the canine histamine H2 receptor occurs at Cys(305) and is important for cell surface targeting.

To determine the presence and functional role of the histamine H2 receptor (H2R) palmitoylation, a receptor with a Cys(305) to Ala (A(305) receptor) mutation was generated. Wild-type (WT) and A(305) receptors were tagged at their N-termini with a hemagglutinin (HA) epitope. WT, but not A(305), receptors incorporated [3H]palmitate by metabolic labeling, indicating that the H2R is palmitoylated at Cys(305). Immunocytochemistry of WT and A(305) receptors expressed in COS7 cells revealed WT receptors to be distributed at the plasma membrane, while the majority of A(305) receptors were localized intracellularly with only a small portion being at the plasma membrane. However, the affinity of the A(305) receptor for tiotidine was comparable to that of the WT receptor. In addition, when the amounts of cell surface receptors as determined by anti-HA antibody binding were equivalent, A(305) receptors mediated production of more cAMP than WT receptors. Preincubation of COS7 cells expressing each receptor with 10(-5) M histamine for 30 min reduced subsequent cAMP production in response to histamine via the receptors to similar extents, indicating that palmitoylation is not necessary for desensitization. In addition, cell surface A(305) receptors were capable of being internalized from the cell surface at a rate and extent similar to those of WT receptors. Finally, CHO cell lines stably expressing either WT or A(305) receptors were incubated with 10(-5) M histamine for 1, 6, 12 and 24 h. Total amounts of WT and A(305) receptors, as determined by tiotidine binding, were reduced by incubation, indicating downregulation. Downregulation of the A(305) receptor was more extensive than that of the WT receptor. Thus, palmitoylation of the H2R might be important for targeting to the cell surface and stability.

Adenylyl Cyclases↗
PubMed2001

Expression of IL-17 mRNA in ovarian cancer.

IL-17 is considered as a proinflammatory cytokine. We have demonstrated IL-17 is an angiogenic factor and promotes tumor growth in murine tumor models. In this report, we investigated the expression of IL-17 mRNA by RT-PCR and the relationship between IL-17 expression and microvascular density in ovarian cancer. IL-17 mRNA was expressed in 11 (64.7%) of 17 ovarian cancer. And the average number of blood vessels observed in IL-17 positive tumors (173.4 +/- 55.1/mm(2)) was significantly higher than that in negative tumors (107.7 +/- 57.8/mm(2)). These results indicated IL-17 is expressed in a considerable proportion of ovarian cancer and promotes tumor angiogenesis. There was no significant relationship between IL-17 expression and clinicopathologic parameters.

Base Sequence↗
PubMed2001

MKK6/3 and p38 MAPK pathway activation is not necessary for insulin-induced glucose uptake but regulates glucose transporter expression.

p38 mitogen-activated protein kinase (MAPK), which is situated downstream of MAPK kinase (MKK) 6 and MKK3, is activated by mitogenic or stress-inducing stimuli, as well as by insulin. To clarify the role of the MKK6/3-p38 MAPK pathway in the regulation of glucose transport, dominant negative p38 MAPK and MKK6 mutants and constitutively active MKK6 and MKK3 mutants were overexpressed in 3T3-L1 adipocytes and L6 myotubes using an adenovirus-mediated transfection procedure. Constitutively active MKK6/3 mutants up-regulated GLUT1 expression and down-regulated GLUT4 expression, thereby significantly increasing basal glucose transport but diminishing transport induced by insulin. Similar effects were elicited by chronic (24 h) exposure to tumor necrosis factor alpha, interleukin-1beta, or 200 mm sorbitol, all activate the MKK6/3-p38 MAPK pathway. SB203580, a specific p38 MAPK inhibitor, attenuated these effects, further confirming that both MMK6 and MMK3 act via p38 MAPK, whereas they had no effect on the increase in glucose transport induced by a constitutively active MAPK kinase 1 (MEK1) mutant or by myristoylated Akt. In addition, suppression of p38 MAPK activation by overexpression of a dominant negative p38 MAPK or MKK6 mutant did not diminish insulin-induced glucose uptake by 3T3-L1 adipocytes. It is thus apparent that activation of p38 MAPK is not essential for insulin-induced increases in glucose uptake. Rather, p38 MAPK activation leads to a marked down-regulation of insulin-induced glucose uptake via GLUT4, which may underlie cellular stress-induced insulin resistance caused by tumor necrosis factor alpha and other factors.

3T3 Cells↗
PubMed2001

Five isoforms of the phosphatidylinositol 3-kinase regulatory subunit exhibit different associations with receptor tyrosine kinases and their tyrosine phosphorylations.

There are five isoforms of the regulatory subunit for the heterodimeric type of phosphatidylinositol 3-kinase. These five regulatory subunit isoforms were overexpressed using an adenovirus transfection system, and their own tyrosine phosphorylations and associations with various tyrosine kinase receptors were investigated. When overexpressed in CHO-PDGFR cells, the associations of these regulatory subunit isoforms with the platelet-derived growth factor receptor were similar. However, when overexpressed in CHO-IR cells, p55gamma exhibited a significantly lower ability to bind with IRS-1 upon insulin stimulation, as compared with other regulatory subunit isoforms. Furthermore, p55alpha and p55gamma were found to be tyrosine-phosphorylated. Finally, interestingly, when overexpressed in CHO-EGFR cells or A431 cells and stimulated with epidermal growth factor (EGF), phosphorylated EGF receptor was detected in p85alpha, p85beta and p50alpha immunoprecipitates, but not in p55alpha and p55gamma immunoprecipitates. In addition, EGF-induced tyrosine phosphorylation was observed in p85alpha, p85beta, p55alpha and p55gamma, but not in p50alpha, immunoprecipitates. Thus, each regulatory subunit exhibits specific responses regarding both the association with tyrosine-phosphorylated substrates and its own tyrosine phosphorylation. These results suggest that each isoform possesses specific roles in signal transduction, based on its individual tyrosine kinase receptor.

Adenoviridae↗
PubMed2001

Bradycardia-induced long QT syndrome caused by a de novo missense mutation in the S2-S3 inner loop of HERG.

Long QT syndrome is a congenital disorder that presents with a defective cardiac ion channel and is either associated with prolonged action potential or, more commonly, known as an acquired form in which "torsades de pointes" type arrhythmias specifically occur after secondary causes. We report a case of a novel HERG mutation (A490T) that caused a bradycardia-associated form of long QT syndrome. A 27-year-old woman exhibited recurrent syncope due to torsades de pointes associated with a disturbance of the cardiac conduction system. By using polymerase chain reaction and single strand conformational polymorphism analyses, we identified a heterozygous single nucleotide substitution of HERG (G to A at nt 1468). This mutational change was not present in 140 Japanese control individuals. Electrophysiological assays for the A490T mutant HERG channel were conducted in the heterologous expression system with COS7 cells. The mutant channel was found to reconstitute functional channel currents, suggesting the homomeric mutant channel was functional. The mutation did not change the properties of the activation gate and inward rectification, however the current density of this mutant channel was small compared with that of wild type HERG. Taken together, this mutant may cause subtle changes in HERG channel functions (I(Kr)) in vivo. In this case, genetic background and unexpected bradycardia may have contributed to the development of long QT syndrome.

Adult↗
PubMed2001

Identification of a new point mutation in the human xanthine dehydrogenase gene responsible for a case of classical type I xanthinuria.

A 60-year-old Japanese man was diagnosed as having hypouricemia at an annual health check-up. The routine laboratory data was not remarkable except that the patient's hypouricemia and plasma levels of xanthine and hypoxanthine were much higher than those of normal subjects. Furthermore, the patient's daily urinary excretion of xanthine and hypoxanthine was markedly increased compared with reference values. The xanthine dehyrogenase activity of the duodenal mucosa was below the limits of detection. Nevertheless, allopurinol was metabolized to oxypurinol in vivo. Based on these findings, a subtype of classical xanthinuria (type I) was diagnosed. The xanthine dehyrogenase protein was detected by Western blotting analysis. Sequencing of the cDNA of the xanthine dehyrogenase obtained from the duodenal mucosa revealed that a point mutation of C to T had occurred in nucleotide 445. This changed codon 149 from CGC (Arg) to TGC (Cys), a finding that has not been previously reported in patients with classical xanthinuria type I.

Allopurinol↗
PubMed2001

G649, an allelic variant of the human H2 receptor with low basal activity, is resistant to upregulation upon antagonist exposure.

Orange et al reported an allelic variant of the human histamine H2 receptor, in which adenine 649 was replaced with guanine, to be more frequent in the schizophrenic population than controls in British Caucasians. The A649 to G change causes an Asn to Asp transition at amino acid position 217 in the third intracellular region, which is postulated to be important for receptor function. Herein, we analyzed the functional significance of this variant using wild-type and variant receptors expressed in Chinese hamster ovary cells. The variant receptor was associated with markedly lower basal cAMP productions than the wild-type receptor. Histamine-dependent cAMP productions via the variant receptor were lower as well. Treatment of cells expressing variant receptors with 10(-5) M ranitidine for 24 h resulted in a reduced degree of receptor upregulation as compared with the wild-type receptor. Thus, this is the first report of an allelic variant of the human H2 receptor which confers altered receptor function. To analyze gastric acid secretion in individuals with this variant, we examined 100 Japanese control subjects. However, neither heterozygotes nor homozygotes were found, suggesting that this variant, if present, is uncommon in the Japanese population.

Alleles↗
PubMed2001

Hereditary benign telangiectasia: image analysis of hitherto unknown association with arteriovenous malformation.

We report 10 patients with hereditary benign telangiectasia (HBT), in whom the age ranged from 1 to 19 years (mean 7.5). The male/female ratio was 1 : 2.3 (3 : 7). Four patients (40%) had congenital lesions. Image analysis with Doppler echogram, angiography and thermography revealed an arterial component in the lesions, consistent with arteriovenous malformation (AVM). This is the first report of HBT in association with AVM.

Adolescent↗
PubMed2001

Relationship between insulin resistance and uremic toxins in the gastrointestinal tract.

The relationship between insulin resistance and local uremic toxins was examined using an oral adsorbent. Fourteen rats demonstrating a diabetic state underwent two-thirds, nephrectomy and were divided into two groups. The control group was fed standard rat chow, and the test group was fed standard rat chow containing 5% AST-120. The target level of blood glucose was achieved by controlling the dosage of exogenous insulin. All rats were sacrificed at week 6. Body weight, blood glucose level, and renal function at week 6 were not significantly different between both groups. However, the mean blood glucose level and the mean dose of exogenous insulin in the AST-120-fed group were significantly reduced as compared with the control group. The results of the present study indicate that administration of an oral adsorbent in diabetic nephropathy decreases the doses of exogenous insulin and improves insulin resistance, and that uremic toxins which exist in the gastrointestinal tract play important roles.

Adsorption↗
PubMed2001

Regulation of phosphoinositide metabolism, Akt phosphorylation, and glucose transport by PTEN (phosphatase and tensin homolog deleted on chromosome 10) in 3T3-L1 adipocytes.

To investigate the roles of PTEN (phosphatase and tensin homolog deleted on chromosome 10) in the regulation of 3-position phosphorylated phosphoinositide metabolism as well as insulin-induced Akt phosphorylation and glucose metabolism, wild-type PTEN and its phosphatase-dead mutant (C124S) with or without an N-terminal myristoylation tag were overexpressed in Sf-9 cells and 3T3-L1 adipocytes using baculovirus and adenovirus systems, respectively. When expressed in Sf-9 cells together with the p110alpha catalytic subunit of phosphoinositide 3-kinase, myristoylated PTEN markedly reduced the accumulations of both phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate induced by p110alpha. In contrast, overexpression of the C124S mutants apparently increased these accumulations. In 3T3-L1 adipocytes, insulin-induced accumulations of phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate were markedly suppressed by overexpression of wild-type PTEN with the N-terminal myristoylation tag, but not by that without the tag. On the contrary, the C124S mutants of PTEN enhanced insulin-induced accumulations of phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. Interestingly, the phosphorylation level of Akt at Thr308 (Akt2 at Thr309), but not at Ser473 (Akt2 at Ser474), was revealed to correlate well with the accumulation of phosphatidylinositol 3,4,5-trisphosphate modified by overexpression of these PTEN proteins. Finally, insulin-induced increases in glucose transport activity were significantly inhibited by the overexpression of myristoylated wild-type PTEN, but were not enhanced by expression of the C124S mutant of PTEN. Therefore, in conclusion, 1) PTEN dephosphorylates both phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate in vivo, and the C124S mutants interrupt endogenous PTEN activity in a dominant-negative manner. 2) The membrane targeting process of PTEN may be important for exerting its function. 3) Phosphorylations of Thr309 and Ser474 of Akt2 are regulated differently, and the former is regulated very sensitively by the function of PTEN. 4) The phosphorylation level of Ser474, but not that of Thr309, in Akt2 correlates well with insulin-stimulated glucose transport activity in 3T3-L1 adipocytes. 5) The activity of endogenous PTEN may not play a major role in the regulation of glucose transport activity in 3T3-L1 adipocytes.

3T3 Cells↗
PubMed2001

Novel protein kinase C delta isoform insensitive to caspase-3.

Protein kinase C delta (PKC delta) plays a key regulatory role in a variety of cellular functions, including apoptosis, as well as cell growth and differentiation. We previously reported that apoptosis was induced by pretreatment with 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), an inhibitor of PKC, in mouse thymocytes. In the present study, we showed that a novel PKC delta isoform (PKC deltaII) was transiently expressed when thymocytes were pretreated with H-7. The analysis of the cDNA encoding PKC deltaII indicated that a 78 bp fragment was inserted into the caspase-3 sensitive site of the original PKC delta (PKC deltaI), presumably by alternative splicing. The PKC deltaII expressed in COS-1 cells was one product with a molecular mass of 81 kDa and with kinase activity similar to that of PKC deltaI. The expressed PKC deltaI protein (78 kDa) was in part cleaved into a 38 kDa fragment in vivo and in vitro, but the PKC deltaII protein was not. Cleavage of the PKC deltaI protein was inhibited by a specific inhibitor of caspase-3, indicating that PKC deltaII is insensitive to caspase-3. The PKC deltaII was highly expressed in the testis and ovary, and at a lower level in the thymocytes, brain and kidney, whereas PKC deltaI was detected in most tissues, suggesting that the function of PKC deltaII is different from that of PKC deltaI.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2001

Insulin resistance with enhanced insulin signaling in high-salt diet-fed rats.

Previous clinical studies showed an apparent correlation between hypertension and insulin resistance, and patients with diabetes are known to have increased blood pressure responsiveness to salt loading. To investigate the effect of high salt intake on insulin sensitivity and the insulin signaling pathway, a high-salt diet (8% NaCl) or a normal diet was given to 7-week-old SD rats for 2 weeks. High salt-fed rats developed slightly but significantly higher systolic blood pressure than controls (133 +/- 2 vs. 117 +/- 2 mmHg, P < 0.001), with no change in food intake or body weight. High salt-fed rats were slightly hyperglycemic (108.5 +/- 2.8 vs. 97.8 +/- 2.5 mg/dl, P = 0.01) and slightly hyperinsulinemic (0.86 +/- 0.07 vs. 0.61 +/- 0.06 ng/ml, P = 0.026) in the fasting condition, as compared with controls. Hyperinsulinemic-euglycemic clamp study revealed a 52.7% decrease in the glucose infusion rate and a 196% increase in hepatic glucose production in high salt-fed rats, which also showed a 66.4% decrease in 2-deoxyglucose uptake into isolated skeletal muscle and a 44.5% decrease in insulin-induced glycogen synthase activation in liver, as compared with controls. Interestingly, despite the presence of insulin resistance, high salt-fed rats showed enhanced insulin-induced tyrosine phosphorylation of insulin receptor substrate (IRS)-1, IRS-2 (liver and muscle), and IRS-3 (liver only). Phosphatidylinositol (PI) 3-kinase activities associated with IRS and phosphotyrosine in the insulin-stimulated condition increased 2.1- to 4.1-fold, as compared with controls. Insulin-induced phosphorylation of Ser-473 of Akt and Ser-21 of glycogen synthase kinase-3 also increased 2.9- and 2-fold, respectively, in the liver of the high salt-fed rats. Therefore, in both the liver and muscle of high salt-fed rats, intracellular insulin signaling leading to PI 3-kinase activation is enhanced and insulin action is attenuated. The hyperinsulinemic-euglycemic clamp study showed that decreased insulin sensitivity induced with a high-salt diet was not reversed by administration of pioglitazone. The following can be concluded: 1) a high-salt diet may be a factor promoting insulin resistance, 2) the insulin-signaling step impaired by high salt intake is likely to be downstream from PI 3-kinase or Akt activation, and 3) this unique insulin resistance mechanism may contribute to the development of diabetes in patients with hypertension.

Animals↗