Biomedical subjects

Hidehiko Saito

Publications and source records attributed to Hidehiko Saito.

At least 19 recordsLinked to original sources

PubMed2005

Identification of amino acid residues essential for heparin binding by the A1 domain of human von Willebrand factor.

Platelet adhesion is mediated by von Willebrand factor (VWF) that binds platelet glycoprotein Ib (GPIb). Previous observations suggested that heparin competitively inhibits the binding of VWF to GPIb and may down-regulate platelet adhesion. We performed charged-to-alanine scanning mutagenesis of domain A1 and studied dose-dependent binding to heparin-Sepharose beads. Mutations at Lys1362 and Arg1395, at which the GPIb binding was markedly decreased, showed 41% and 42% binding, respectively. Clustered mutations in the segments 1332KDRKR1336 and 1405KKKK1408, which have been proposed as heparin binding sequences, showed 72% and 52% binding, respectively. However, single alanine substitutions within these clusters showed normal binding. Our findings suggest that heparin may inhibit the binding of VWF to GPIb by interacting with GPIb binding and interpret why some hemorrhagic complications of heparin therapy are not predictable based on techniques for monitoring the conventional anticoagulant effects of heparin.

Amino Acid Substitution↗

PubMed2005

Congenital macrothrombocytopenias.

Congenital macrothrombocytopenias comprise a heterogeneous group of rare disorders, characterized by abnormal giant platelets, thrombocytopenia and bleeding tendency with variable severity. Many of these disorders share common clinical and laboratory features, making accurate diagnosis difficult and patients are often misdiagnosed with and treated for idiopathic thrombocytopenic purpura. Recent progress in the elucidation of underlying defects and further developments of specific diagnostic techniques for several congenital macrothrombocytopenias have renewed our approach to the classification and the diagnosis of the disease. This review summarizes the current knowledge on the clinical and laboratory features of common congenital macrothrombocytopenias and discusses how that knowledge aids in making a proper diagnosis.

Blood Platelets↗

PubMed2005

Transcriptional regulation of FKLF-2 (KLF13) gene in erythroid cells.

FKLF-2 (KLF13) was cloned from fetal globin-expressing tissues and has been shown to be abundantly expressed in erythroid cells. In this study we examined the transcriptional regulation of the KLF13 gene. A 5.5 kb 5' flanking region cloned from mouse erythroleukemia (MEL) cell genomic DNA showed that major cis regulatory activities exist in the 550 bp sequence to the unique transcription start site, and that the promoter is more active in K562 cells than in COS-7 cells. The promoter was trans-activated by co-expressed GATA-1 through the sequence containing two CCAAT motifs, suggesting that GATA-1 is involved in the abundant expression of KLF13 mRNA in the erythroid tissue. Dual action, i.e. activating effect in COS-7 and repressive effect in K562 cell, was observed on its own promoter, suggesting a feedback mechanism for the transcriptional control of the KLF13 gene in the erythroid environment. These findings provide an insight on the mechanism of inducible mRNA expression of the KLF13 gene in erythroid cells.

Animals↗

PubMed2005

Leukemic relapse in the central nervous system after allogeneic stem cell transplantation with complete remission in the bone marrow and donor-type chimerism: report of two cases.

We studied two cases with leukemia that relapsed in the central nervous system (CNS) after allogeneic stem cell transplantation. One patient underwent peripheral blood stem cell transplantation (SCT) from a related, yet haplotype-mismatched, donor for chronic myelomonocytic leukemia. She was kept in complete remission (CR) in the bone marrow (BM) for 7 months, until relapse in the cerebrospinal fluid (CSF) was evident. In the other patient, with acute lymphoblastic leukemia, systemic relapse occurred when he was still on immunosuppression 6 months after SCT from an unrelated donor. After induction chemotherapy following cessation of immunosuppression, the BM examination proved CR. During consolidation chemotherapy, however, he developed leukemic dissemination in the CSF, despite the fact that the BM was in CR. Chimerism status in the BM mononuclear cells and fractionated peripheral blood (PB) cells (granulocytes, T-lymphocytes, and the others) was assessed by short tandem repeat analysis. In both patients, the BM cells and all the fractions of the PB cells proved donor-type chimeras. These results seem to suggest that the graft-versus-leukemia effects might not be as effective in the CNS as in the BM, even when complete T-lymphoid chimerism is achieved.

Adult↗

PubMed2005

First description of somatic mosaicism in MYH9 disorders.

MYH9 disorders are characterized by giant platelets, thrombocytopenia, and Dohle body-like cytoplasmic granulocyte inclusion bodies that result from mutations in MYH9, which encodes non-muscle myosin heavy chain-A (NMMHCA). These disorders are known to be transmitted in an autosomal dominant manner, although about 20% of cases are considered to be sporadic. We report here the first case of a MYH9 disorder because of somatic mosaicism. The patient was the father of a male with typical May-Hegglin anomaly. The father had normal platelet counts, however, both normal-sized and giant platelets were observed on his peripheral blood smears. In addition, 14% of neutrophils contained inclusion bodies and the rest showed a normal morphology. Quantitative fluorescent polymerase chain reaction analysis showed that only 6% of DNA from peripheral blood leucocytes harboured the mutation. The mosaicism was demonstrated at a similar rate in different tissues, buccal mucosa cells and hair bulb cells, implying that the mutation had occurred before gastrulation. Mosaicism might account for some de novo mutations in MYH9 disorders.

Base Sequence↗

PubMed2005

Detection of unique neutrophil non-muscle myosin heavy chain-A localization by immunofluorescence analysis in MYH9 disorder presented with macrothrombocytopenia without leukocyte inclusions and deafness.

MYH9 disorders are autosomal-dominant macrothrombocytopenias with leukocyte inclusions caused by mutations in the MYH9 gene, which encodes the non-muscle myosin heavy chain-A (NMMHCA). We report a patient with an MYH9 disorder who presented with macrothrombocytopenia without leukocyte inclusions and severe bilateral sensory deafness. Conventional May-Grunwald-Giemsa staining failed to detect granulocyte cytoplasmic inclusions, whereas immunofluorescence analysis clearly demonstrated abnormal neutrophil NMMHCA localization. Genetic analyses revealed a novel heterozygous 18 base deletion in MYH9, leading to a six-amino acid in-frame deletion (N76_S81del) in NMMHCA. These results further support the usefulness of immunofluorescence analysis in differential diagnosis of MYH9 disorders.

Amino Acid Sequence↗

PubMed2005

Long-term outcomes for unselected patients with acute myeloid leukemia categorized according to the World Health Organization classification: a single-center experience.

The actual utility of a new classification system of acute myeloid leukemia (AML) recently introduced by the World Health Organization (WHO) has not been thoroughly investigated yet. In this study, we evaluated long-term outcomes of unselected AML patients categorized according to the new WHO classification. Between 1990 and 2002, 109 adult AML cases were referred to our hospital. For the entire population, the median survival duration was 1.2 yr with a 5-yr survival rate of 31%. AML with recurrent genetic abnormalities accounted for 26%, AML with multilineage dysplasia for 29%, therapy-related AML for 13%, and AML not otherwise categorized for 32% of classifiable cases. Among the four groups, a significant difference was observed in terms of overall survival (P < 0.0001). Univariate analysis showed that six variables affected survival: cytogenetic risk, age, multilineage dysplasia, prior chemo/radiotherapy, type of treatment (intensive or palliative), and transplantation. However, in multivariate analysis no adverse prognostic impact of multilineage dysplasia and prior chemo/radiotherapy was detected (P = 0.4979 and 0.8702), whereas cytogenetic risk and patient age maintained their prognostic value (P = 0.0005 and 0.0100). These results indicate that outcomes for AML patients appear to be distinguished on the basis of the WHO classification, but the prognostic significance of multilineage dysplasia and prior therapy is lost after adjusting for cytogenetic risk and age. Our findings suggest that the WHO classification may be strengthened by greater emphasis on genetic/cytogenetic information.

Adolescent↗

PubMed2005

Long-term results of a multicenter randomized, comparative trial of modified CHOP versus THP-COP versus THP-COPE regimens in elderly patients with non-Hodgkin's lymphoma.

In treating elderly non-Hodgkin's lymphoma (NHL) patients, it is particularly important to use drugs that have a low incidence of adverse events and high efficacy. In this multicenter study, THP (pirarubicin)-COP (cyclophosphamide, vincristine, and prednisolone) was compared to two thirds dosage of full CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) regimen with regard to both adverse events and efficacy. For a third group, etoposide (E) was added to the THP-COP regimen (THP-COPE) in order to achieve high dose-intensity. Subjects were 486 previously untreated patients, aged 65 or older (range, 65-92 years; median, 74 years), with NHL. Subjects were randomly assigned to receive THP-COP, two thirds CHOP, or THP-COPE. Four hundred and forty-three patients were assessed for response and followed for 8 years after the last subject registered. The complete remission rates for the THP-COP, CHOP, and THP-COPE groups were 42.5%, 41.4%, and 48.0%, respectively. There was no difference in overall survival or progression-free survival among these 3 groups. In aggressive lymphoma, there was also no difference in complete response (CR) rate (45.3% in THP-COP, 44.9% in CHOP, 48.0% in THP-COPE), overall survival, and progression-free survival among these groups. The 5- and 8-year survival rates for all patients were 29.4% and 18.7%, respectively. The 5- and 8-year survival rates for patients with aggressive lymphoma were 27.4% and 17.4%, respectively. Although long-term survival for patients with aggressive lymphoma on our regimens was not worse compared to previous reports, the CR rate was lower. Because severe adverse events were not observed, higher dose chemotherapy may be directed to achieve better CR rates. In patients with T-cell-type lymphoma, the CR rate was greater after treatment with THP-COP (51.4%) or THP-COPE (57.7%) compared to treatment with CHOP (19.4%). Pirarubicin may be more useful for T-cell lymphoma than doxorubicin. Because adverse cardiac events were reported only in CHOP, adverse cardiac events might be low in the THP group.

Aged↗

PubMed2004

Targeted disruption of mouse ortholog of the human MYH9 responsible for macrothrombocytopenia with different organ involvement: hematological, nephrological, and otological studies of heterozygous KO mice.

Among three different isoforms of non-muscle myosin heavy chains (NMMHCs), only NMMHCA is associated with inherited human disease, called MYH9 disorders, characterized by macrothrombocytopenia and characteristic granulocyte inclusions. Here targeted gene disruption was performed to understand fundamental as well as pathological role of the gene for NMMHCA, MYH9. Heterozygous intercrosses yielded no homozygous animals among 552 births, suggesting that MYH9 expression is required for embryonic development. In contrast, MYH9+/- mice were viable and fertile without gross anatomical, hematological, and nephrological abnormalities. Immunofluorescence analysis also showed the normal cytoplasmic distribution of NMMHCA. We further measured the auditory brainstem response and found two of six MYH9+/- mice had hearing losses, whereas the remaining four were comparable to wild-type mice. Such observation may parallel the diverse expression of Alport's manifestations of human individuals with MYH9 disorders and suggest the limited requirement of the gene for maintenance and function of specific organs.

Animals↗

PubMed2004

Molecular cloning and characterization of ZFF29: a protein containing a unique Cys2His2 zinc-finger motif.

We have cloned a gene, ZFF29 (zinc-finger protein of human fetal liver erythroid cells 29), from human fetal liver erythroid cells. Two types of mature mRNA were identified and designated ZFF29a and ZFF29b. In human genome the ZFF29 gene is on chromosome 9q, and the two forms are splice variants. There is a unique transcription start site, which predicts major mRNAs composed of 2485 bases for ZFF29a and 1801 bases for ZFF29b. The anticipated mRNAs were demonstrated in K562 cells, but not in any adult human tissues examined by Northern blotting. In the mouse, reverse transcription-PCR revealed that the ZFF29 mRNA is present in adult bone marrow and ovary at a higher level than in any other tissues examined. These findings suggest that ZFF29 proteins are expressed in embryonic/fetal erythroid tissues. The deduced polypeptide chains of ZFF29a and ZFF29b are composed of 306 and 350 amino acids respectively. A unique zinc-finger motif composed of two contiguous Cys(2)His(2)-type fingers is common to both forms of ZFF29. They are nuclear proteins and ZFF29b, but not ZFF29a, is an activator of erythroid gene promoters.

Alternative Splicing↗

PubMed2004

Aging and plasminogen activator inhibitor-1 (PAI-1) regulation: implication in the pathogenesis of thrombotic disorders in the elderly.

Thrombotic cardiovascular diseases increase in incidence in the elderly, a tendency dependent on the age-related changes in vascular and hemostatic systems that include platelets, coagulation, and fibrinolytic factors as well as in the endothelium. The hypercoagulability of and advanced sclerotic changes in the vascular wall may contribute to the increased incidence of thrombosis in the elderly. One of the important key genes for aging-associated thrombosis is plasminogen activator inhibitor-1 (PAI-1), a principal inhibitor of fibrinolysis. The expression of PAI-1 is not only elevated in the elderly but also significantly induced in a variety of pathologies associated with the process of aging. These conditions include obesity, insulin resistance, emotional stress, immune responses, and vascular sclerosis/remodeling. Several cytokines and hormones, including tumor necrosis factor-alpha, transforming growth factor-beta, angiotensin II, and insulin, positively regulate the gene expression of PAI-1. The recent epidemic in obesity with aging in the industrialized society may heighten the risk for thrombotic cardiovascular disease because adipose tissue is a primary source of PAI-1 and cytokines. Emotional or psychosocial stress and inflammation also cause the elevated expression of PAI-1 in an age-specific pattern. Thus, PAI-1 could play a key role in the progression of cardiovascular aging by promoting thrombosis and vascular (athero)sclerosis. Further studies on the genetic mechanism of aging-associated PAI-1 induction will be necessary to define the basis for cardiovascular aging in relation to thrombosis.

Adipose Tissue↗

PubMed2004

Expression cloning of oligomerization-activated genes with cell-proliferating potency by pseudotype retrovirus vector.

We developed a method of clone proliferation promoting fusion genes whose proteins were activated by protein oligomerization through the helix-loop-helix region (PNT domain) of TEL. We inserted a cDNA library downstream of the PNT domain with a retrovirus vector. The resulting retrovirus infected cytokine-dependent 32D cells and cells with cytokine-independent growth were analyzed for the inserted cDNA. We cloned 25 independent fusion genes including seven kinds of partner genes. Six of the seven were a fusion of TEL with protein tyrosine kinase, LYN, HCK, FGR, SYK, FLT3, and TYK2. A serine/threonine kinase, ARAF1, was also found to fuse with TEL. These kinase fusion proteins included kinase domains with proper reading frames. These fusions may be a useful model for clarifying the downstream signal transduction of constitutive active kinase and this expression cloning method may provide a new tool with which to study cell proliferation signalling.

Animals↗

PubMed2004

Identification of the amino acid residues of the platelet glycoprotein Ib (GPIb) essential for the von Willebrand factor binding by clustered charged-to-alanine scanning mutagenesis.

At the site of vascular injury, von Willebrand factor (VWF) mediates platelet adhesion to subendothelial connective tissue through binding to the N-terminal domain of the alpha chain of platelet glycoprotein Ib (GPIbalpha). To elucidate the molecular mechanisms of the binding, we have employed charged-to-alanine scanning mutagenesis of the soluble fragment containing the N-terminal 287 amino acids of GPIbalpha. Sixty-two charged amino acids were changed singly or in small clusters, and 38 mutant constructs were expressed in the supernatant of 293T cells. Each mutant was assayed for binding to several monoclonal antibodies for human GPIbalpha and for ristocetin-induced and botrocetin-induced binding of 125I-labeled human VWF. Mutations at Glu128, Glu172, and Asp175 specifically decreased both ristocetin- and botrocetin-induced VWF binding, suggesting that these sites are important for VWF binding of platelet GPIb. Monoclonal antibody 6D1 inhibited ristocetin- and botrocetin-induced VWF binding, and a mutation at Glu125 specifically reduced the binding to 6D1. In contrast, antibody HPL7 had no effect for VWF binding, and mutant E121A reduced the HPL7 binding. Mutations at His12 and Glu14 decreased the ristocetin-induced VWF binding with normal botrocetin-induced binding. Crystallographic modeling of the VWF-GPIbalpha complex indicated that Glu128 and Asp175 form VWF binding sites; the binding of 6D1 to Glu125 interrupts the VWF binding of Glu128, but HPL7 binding to Glu121 has no effect on VWF binding. Moreover, His12 and Glu14 contact with Glu613 and Arg571 of VWF A1 domain, whose mutations had shown similar phenotype. These findings indicated the novel binding sites required for VWF binding of human GPIbalpha.

Alanine↗

PubMed2004

Increased expression of plasminogen activator inhibitor-1 in cardiomyocytes contributes to cardiac fibrosis after myocardial infarction.

Plasminogen activator inhibitor-1 (PAI-1) plays a critical role in tissue fibrosis by inactivating matrix metalloproteinases, which might effect on the progression of left ventricular dysfunction. However, little has been known about the expression of PAI-1 during cardiac remodeling. We used a mouse model of myocardial infarction (MI) by coronary ligation, in which the progression of left ventricular remodeling was confirmed by echocardiography. Histological examination showed that interstitial and perivascular fibrosis progressed in the post-MI (PMI) heart at 4 weeks after the procedure. We observed the dramatic induction of cardiac PAI-1 mRNA and PAI-1 antigen in plasma in the PMI mice, as compared with the sham-operated (sham) mice. In situ hybridization analysis demonstrated that strong signals for PAI-1 mRNA were localized to cardiomyocytes in the border of infarct area and around fibrous lesions, and to perivascular mononuclear cells, which seemed to be mast cells, only in hearts of the PMI mice. Importantly, less development of cardiac fibrosis after MI was observed in mice deficient in PAI-1 as compared to wild-type mice. The mRNA expression of cytokines, transforming growth factor-beta, and tumor necrosis factor-alpha, was also increased in hearts of the PMI mice, but not in the sham mice. These observations suggest that cardiomyocytes and mast cells contribute to the increased PAI-1 expression, resulting in the development of interstitial and perivascular fibrosis in the PMI heart, and that the regional induction of cytokines may be involved in this process.

Animals↗

PubMed2004

Identification of protein Salpha gene mutations including four novel mutations in eight unrelated patients with protein S deficiency.

Eight distinct and potentially causative mutations were identified in eight unrelated Japanese patients with protein S (PS) deficiency, by direct DNA sequencing of the protein Salpha (PSalpha) gene-specific polymerase chain reaction products of all 15 exons and exon/intron boundaries. There were five missense mutations, including two novel mutations (Cys80Tyr and Arg314His), and three showed a major impact on the expected gene products: novel mutations of a 5-bp deletion (delCTCTG887:Cys206Stop) and a nonsense mutation (Glu208Stop), as well as a previously reported splice site (exon 10 +5 A-->G) mutation. One of the patients showed compound heterozygosity for delCTCTG887 and 732A-->G. Investigation for the cosegregation state of these two mutations with PS deficiency in the patient's family suggested that the delCTCTG887 mutation was responsible for the abnormal phenotype and that the 732A-->G (Lys155Glu) mutation did not appear to play a key role. However, we also identified the same 732A-->G (Lys155Glu) mutation in an unrelated patient with apparent PS deficiency with severe pulmonary embolism, and found that this mutation seemed to cosegregate with a PS-deficient state in her family members. These data implied that unknown factor(s) other than the 732A-->G mutation itself might influence phenotypic expression of PS status in different individuals.

Adult↗

PubMed2004

Functional regulation of GATA-2 by acetylation.

The transcription factor GATA-2 is expressed in hematopoietic stem and progenitor cells and is functionally implicated in their survival and proliferation. In the present study, we show that GATA-2 exists as an acetylated protein in immature precursor cells, KG1. GATA-2 was acetylated in vitro by p300 and GCN5. We have identified multiple acetylation sites by p300 on GATA-2, which include sites outside the zinc finger domain. We confirmed that GATA-2 acetylation occurred in transiently transfected 293T cells at sites similar to those induced by p300 in vitro. We have successfully shown that acetylation of GATA-2 in vitro increased its DNA-binding activity. In addition, GATA-2 displayed a transcriptional synergism with p300 that was impaired by mutation of each acetylation site. More importantly, each mutation in the acetylation sites of GATA-2 abolished its growth inhibitory effect on an interleukin-3-dependent progenitor, 32D. We conclude that acetylation provides multiple control points for the regulation of GATA-2 function.

Acetylation↗

PubMed2004

A unique immunofluorescence method promotes accurate diagnosis in MYH9 disorders: a case report.

The identification of a mutation in the MYH9 gene in hereditary macrothrombocytopenia has established a distinct entity proposed as "MYH9 disorders," which previously have often been misdiagnosed as chronic immune thrombocytopenic purpura. The authors describe clinical and laboratory characterization of a family with the disorder demonstrating giant platelets, thrombocytopenia, and leukocyte inclusion bodies. The authors emphasize the efficacy of a unique immunofluorescence method for the nonmuscle myosin heavy chain A in the diagnosis, because it is more sensitive than May-Grünwald-Giemsa staining and more practical than electron microscopy or direct sequencing. MYH9 disorders may be much more common than previously realized if accurately diagnosed.

Blood Platelets↗

PubMed2004

[Factor XI].

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Biomarkers↗