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S Kosugi

Publications and source records attributed to S Kosugi.

At least 55 records · Page 3Linked to original sources
PubMed1998

A Gln747-->Pro substitution in the IIb subunit is responsible for a moderate IIbbeta3 deficiency in Glanzmann thrombasthenia.

To clarify a molecular defect responsible for moderate alphaIIb beta3 deficiency, we examined two unrelated patients, MT and MS, suffering from type II and type I Glanzmann thrombasthenia (GT), respectively. Sequence analysis of polymerase chain reaction (PCR) fragments derived from platelet mRNA showed a single A-->C substitution at nucleotide (nt) 2334 leading to a Gln747--> Pro in alphaIIb in both patients. Allele-specific restriction enzyme analysis (ASRA) of genomic DNA demonstrated that patient MT was homozygous for the Gln747-->Pro substitution and patient MS was compound heterozygous for this substitution and for an RNA splice mutation at the consensus sequence of the splice acceptor site of exon 18 (AG-->AA). Furthermore, ASRA showed that, among 17 unrelated Japanese GT patients, this Gln747-->Pro substitution was detected in 4 patients, including MT and MS (homozygous, 2 patients; heterozygous, 2 patients). Cotransfection of Pro747alphaIIb and beta3 constructs into 293 cells resulted in moderate reduction in the amount of alphaIIb beta3 within the transfected cells as well as on the cell surface. However, Pro747alphaIIb beta3 bound the ligand mimetic monoclonal antibody (MoAb) PAC-1 after activation of alphaIIb beta3 by the MoAb PT25-2, suggesting that the mutant alphaIIb beta3 possesses the ligand-binding function. The association between the mutant proalphaIIb and beta3 was not disturbed. Surface labeling and pulse chase study showed that the Gln747-->Pro substitution moderately impaired both intracellular transport of the alphaIIb beta3 heterodimers to the Golgi apparatus and endoproteolytic cleavage of proalphaIIb into heavy and light chains. By contrast, replacement of Gln747 with Ala by mutagenesis did not impair alphaIIbbeta3 expression on the cell surface. These results suggest that the presence of Pro, rather than the absence of Gln, at amino acid residue 747 on alphaIIb is responsible for moderate alphaIIbbeta3 deficiency.

Alleles↗
PubMed1998

Allelic loss analysis of gamma-ray-induced mouse thymic lymphomas: two candidate tumor suppressor gene loci on chromosomes 12 and 16.

A total of 429 gamma-ray-induced thymic lymphomas were obtained from F1 and backcross mice between BALB/c and MSM strains, about a half of which carried a p53-deficient allele. A genome-wide allelic loss analysis has revealed two loci exhibiting frequent allelic losses but no allelic preference, one is localized within a 2.9 cM region between D12Mit53 and D12Mit279 loci on chromosome 12, and the other is near the D16Mit122/D16Mit162 loci on chromosome 16. The frequency of allelic loss in the D12Mit279 region is 62% and does not differ in tumors between the presence and absence of the p53-deficient allele. In contrast, the loss frequency of D16Mit122 is raised by the existence of p53-deficient allele: 62% for p63(-/+) and 13% for p53(+/+), suggesting co-operative function of the two losses. The D12Mit279 and D16Mit122 regions probably harbor different types of tumor suppressor gene that play key roles in lymphoma development.

Animals↗
PubMed1998

Immunization with the "immunogenic peptide" of TSH receptor induces oligoclonal antibodies with various biological activities.

Balb/c mice were immunized with a synthetic peptide (P354-14) corresponding to "the immunogenic peptide" of human thyrotropin receptor (hTSH-R). Through screening for binding to the peptide, we obtained several monoclonal antibodies with various biological activities: thyroid stimulation (SAb), inhibition of TSH stimulation (BAb) and no significant effect on cAMP production. One of the stimulatory clones was further studied. This clone enhanced cAMP production in Cos-7 cells transformed with the truncated TSH-R cDNA deleting the immunogenic peptide. These results indicated that the immunogenic peptide of the TSH-R induces oligoclonal anti-TSH-R antibodies, although the region is not essential for the functional epitope.

Animals↗
PubMed1998

Severe testotoxicosis phenotype associated with Asp578-->Tyr mutation of the lutrophin/choriogonadotrophin receptor gene.

Testotoxicosis is a form of male precocious puberty caused by heterogeneous activating mutations in the gene for the lutrophin/choriogonadotrophin receptor (LHR). A patient with an unusually early and severe presentation of testotoxicosis, including profound Leydig cell hyperplasia, was found to have a sporadic mutation encoding Asp578-->Tyr. The severe testotoxicosis phenotype appears to be related to the strongly activating nature of the Tyr substitution.

Aspartic Acid↗
PubMed1998

High prevalence of T354P sodium/iodide symporter gene mutation in Japanese patients with iodide transport defect who have heterogeneous clinical pictures.

A missense and loss of function mutation of the Na+/I- symporter (NIS) gene, T354P [Thr354-->Pro (ACA-->CCA)], was found in the homozygous state in two unrelated Japanese patients with iodide transport defect. In this study we have identified the homozygous T354P NIS germline mutation in seven Japanese patients, including one previously reported, from five unrelated families. No other nucleotide changes were found in the coding regions and the exon-intron boundaries of the NIS gene in these seven patients. These results suggest a common prevalence of the T354P mutation in Japanese patients. Although these seven patients have the identical NIS mutation, T354P, marked heterogeneity in clinical pictures, especially concerning goiter and hypothyroidism, were noted among them. Therefore, another factor(s), but not the nature of the NIS mutation, may account for the clinical heterogeneity among patients with the iodide transport defect. We have previously reported that the NIS messenger ribonucleic acid was markedly increased in the thyroid of a patient with the homozygous T354P mutation. In this study we demonstrated that the NIS proteins in the patients' thyroids were significantly increased (approximately 10-fold) by Western blot analysis of integral membrane proteins using an antibody against the C-terminal peptide of the human NIS. Furthermore, we showed by immunohistochemical staining that the T354P mutant NIS proteins were overexpressed in the basal and lateral plasma membranes of patients' thyrocytes.

Adult↗
PubMed1998

A homozygous inactivating mutation in the parathyroid hormone/parathyroid hormone-related peptide receptor causing Blomstrand chondrodysplasia.

We describe a patient with Blomstrand chondrodysplasia, a lethal genetic disorder characterized by extremely advanced endochondral bone maturation, in whom a homozygous missense mutation is present in the gene coding for the PTH/PTHrP receptor that leads to the substitution of a proline for a leucine in the N-terminal portion of the receptor (P132L). PTH-induced cAMP accumulation was severely reduced in COS-7 cells expressing P132L receptors compared to that of cells expressing wild-type receptors, and PTH-induced inositol phosphate accumulation was not detectable in cells expressing the mutant receptor. Similar results were obtained using PTHrP as an agonist. Maximal specific binding of radioiodinated [Tyr36]PTHrp(1-36) by cells transfected with the P132L receptor was < 10% of that observed for cells transfected with the wild-type receptor. Despite the reduction in radioligand binding to P132L receptors, the intensity and distribution of the fluorescent signal resulting from the expression of receptors fused to GFP were similar for cells transfected with the wild-type and mutant P132L receptors, suggesting a similar degree of cell surface expression. These results firmly establish the role of abnormalities in the PTH/PTHrP receptor in the pathogenesis of Blomstrand chondrodysplasia, and thereby confirm the importance of signaling through the PTH/PTHrP receptor in human fetal skeletal development. Because the amino-acid mutated in the patient described here is otherwise conserved in all mammalian class II G protein-coupled receptors, this abnormality may provide insights into structural features needed for the normal function of this family of receptors.

Animals↗
PubMed1998

Multiple inflammatory pseudotumors of the liver associated with acute myeloblastic leukemia.

A 26-year-old man, diagnosed with acute myelogenous leukemia had multiple inflammatory pseudotumors (IPT) in the liver. The patient presented complete remission after remission induction therapy, and then showed right upper quadrant discomfort and intermittent fever. An ultrasonography disclosed multiple hypoechoic nodules in the liver. A biopsy of the nodules showed focal liver cell necrosis with scant inflammatory cells, compatible with IPT. After several courses of chemotherapy, the nodules in the liver increased. The second liver biopsy of the nodule showed fibrosis. Multiple IPTs in the liver should be distinguished from abscess and metastatic nodules.

Adult↗
PubMed1998

[The developmental process of employee maladjustment in work place].

A causal model of job stressors and stress reactions was examined to clarify the developmental process of employee maladjustment in work place. Two thousand seven hundred twenty-eight (2728) employees of a research institute in the automobile industry completed Job Stress Scale (JSS), which measured job stressors, stress reactions, coping strategies, and social support. Three hundred ninety-two (392) employees with high stress reaction scores were interviewed to obtain information to construct a theoretical model. Then, the model was evaluated with covariance structure analysis. Results showed that the quantitative job stressors had only an indirect effect, mediated by fatigue and irritability, on mental instability, whereas qualitative ones had both direct and indirect effects. The findings suggest that the developmental processes of employee maladjustment in work place differ depending on the kind of job stressors they experience.

Adaptation, Psychological↗
PubMed1998

[AIDS counseling].

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Brain Chemistry↗
PubMed1998

An anionic residue at position 564 is important for maintaining the inactive conformation of the human lutropin/choriogonadotropin receptor.

Gonadotropin-independent, male-limited precocious puberty is caused by a variety of mutations in the lutropin/choriogonadotropin receptor (LHR) that produce constitutive receptor activation. Two of these mutations encode replacement of conserved aspartate residues at positions 564 and 578 with glycine. We previously used site-directed mutagenesis to study the functional role of the Asp578 side chain in transmembrane helix 6, and concluded that it is its ability to serve as a properly positioned interhelical hydrogen bond acceptor, rather than its negative charge, that is important for stabilizing the inactive state of the LHR. We now report the effects of substituting seven different amino acids for the Asp564 residue located at the carboxyl terminus of the third intracellular loop. Glycine, alanine, valine, leucine, phenylalanine, and asparagine produced constitutive activation in a COS-7 cell expression system (3-5-fold increase in basal cAMP), but glutamate did not, indicating that a negative charge at position 564 may be important for maintaining the inactive LHR conformation. Characterization of double-mutant receptors showed that certain substitutions at Asp564 and Asp578 have a cumulative effect on basal receptor activity, perhaps because they mimic different aspects of the activation process normally triggered by hormone binding.

Amino Acid Sequence↗
PubMed1998

Tumor recurrence in patients with early gastric cancer: a clinicopathologic evaluation.

We conducted a retrospective study on 711 patients with early gastric cancer. Twenty-two patients (4.0%) developed recurrent disease and 21 died of recurrence during this study. One hundred and sixty-three patients died of unrelated or unknown causes. The recurrence patterns of 22 patients were as follows: hematogeneous metastasis to the liver in 11 patients, peritoneal dissemination in 3, recurrence in the remnant stomach in 3, and in the distant lymphonodes in 1. The mean survival period of patients with recurrent disease was 50.4 months, and 7 of these patients (31.8%) died more than 5 years after surgery. A retrospective clinicopathologic evaluation of the 22 patients and 526 patients without recurrence revealed significant differences between the two groups with respect to mean age at the time of surgery (62.5 years in the recurrent group vs 57.3 years in the nonrecurrent group), tumor size (41.2 vs 30.6 mm), depth of invasion (submucosal cancer: 19 vs 256), lymphnode metastasis (11 vs 48), lymphatic (11 vs 89) and venous (7 vs 18) invasion, and operative curability (curability B: 8 vs 48). Three patients with intramucosal cancer who died of hematogenous and/or peritoneal recurrence within 7 years after surgery had neither lymphnode metastasis nor lymphatic or venous invasion, suggesting that new techniques are needed for prediction of recurrent disease in patient with early gastric cancer.

Adult↗
PubMed1998

[Disorders caused by mutations of the thyrotropin receptor].

Since 1993, a number of mutations of the thyrotropin receptor(TSHR) gene causing human diseases have been reported; activating TSHR somatic mutations causing autonomously functioning thyroid nodules, activating TSHR germ-line mutations causing familial non-autoimmune hyperthyroidism, and inactivating TSHR germ-line mutations causing hypothyroidism due to TSH unresponsiveness. Activating TSHR mutations increase second messenger signals without stimulation of TSH or thyroid stimulating antibody, conferring autonomous growth and function upon thyroid cells. Most of activating TSHR mutations are located in the transmembrane domain of the receptor. One of most important mechanisms how these mutants activate the receptor constitutively is that inter-helical bonding(s) maintained in the silent receptor is/are disrupted by the mutations. Further investigation of activating mutations will provide insight into normal activating mechanism of the receptor.

Graves Disease↗
PubMed1997

Markedly reduced expression of platelet c-mpl receptor in essential thrombocythemia.

Thrombopoietin (TPO) is implicated as a primary regulator of megakaryopoiesis and thrombopoiesis through binding to the cytokine receptor c-Mpl (the product of the c-mpl proto-oncogene). In an effort to determine the pathophysiological role of TPO-c-Mpl system in essential thrombocythemia (ET), we have examined the levels of serum TPO and the expression and function of platelet c-Mpl in 17 patients with ET. In spite of extreme thrombocytosis, serum TPO levels were slightly elevated or within normal range in most, if not all, patients with ET (mean +/- SD, 1.31 +/- 1.64 fmol/mL), as compared with normal subjects (0.76 +/- 0.21 fmol/mL). Flow cytometric and Western blot analyses revealed that the expression of platelet c-Mpl was strikingly reduced in all patients with ET. Furthermore, the expression of platelet c-mpl mRNA was found to be significantly decreased in the ET patients tested. In contrast, almost identical levels of GPIIb/IIIa protein and mRNA were expressed in platelets from ET patients and normal controls. In addition to expression level, activation state of platelet c-Mpl was investigated in ET patients. Immunoblotting with anti-phosphotyrosine antibody showed that no aberrant protein-tyrosine phosphorylation was observed in platelets of ET patients before treatment with TPO, and the levels of TPO-induced protein-tyrosine phosphorylation, including c-Mpl-tyrosyl phosphorylation, roughly paralleled those of c-Mpl expression, suggesting that c-Mpl-mediated signaling pathway was not constitutively activated in platelets of ET patients. These results suggested that the TPO-c-Mpl system may not be directly linked to pathogenesis of ET, and that gene(s) mutated in ET may be important in regulating the levels of c-mpl gene expression in addition to the growth and differentiation of multipotential hematopoietic stem cells.

Adolescent↗
PubMed1997

Genetic and physical delineation of the region of the mouse deafness mutation shaker-2.

A total of 951 backcross progeny have been obtained from a backcross segregating for the mouse deafness mutation, shaker-2(sh-2). Linkage analysis provides a detailed genetic map in the vicinity of sh-2 which comprises 40 backcross mice identified as recombinant within a 4 cM region. This allows construction of a contig consisting of 21 BAC clones across an approximately 700-kb region of sh-2. This covers the entire nonrecombinant region of sh-2 and is therefore useful to facilitate the identification of genes in the sh-2 region.

Animals↗
PubMed1997

Aspartate-474 in the first exoplasmic loop of the thyrotropin receptor is crucial for receptor activation.

Asp-474 in the first exoplasmic loop of the thyrotropin receptor (TSHR), which is conserved among all glycoprotein hormone receptors, was mutated to Glu which is similarly charged but is longer by one methylene group and expressed in Cos-7 cells. Cells expressing this mutant receptor showed markedly impaired TSH- and TSAb (thyroid stimulating antibody)-stimulated cAMP responses with no effect on TSH binding affinity when compared with cells expressing a similar number of wild-type receptors. These results suggest the importance of Asp-474 in TSHR in receptor activation as demonstrated for LHR (lutropin receptor), but this, unlike LHR, is not due to the electrostatic interaction of this Asp residue with the alpha-subunit Lys-91 of the hormone.

Animals↗
PubMed1997

Different electrophysiological character of I-, ClO4-, and SCN- in the transport by Na+/I- symporter.

The electrophysiological characteristics of the Na+/I- symporter were examined using the Chinese hamster ovary (CHO) cell line, which was transfected with the rat Na+/I- symporter gene and stably expressed the Na+/I- symporter. In this cell line, iodide uptake was dependent on Na+, and kinetic studies revealed that the K(m) for iodide was 35 microM, similar to that of FRTL-5 cells. The maximal velocity at the cell protein level was 6- to 10-fold higher than in FRTL-5 cells. ClO-4 and SCN- dose-dependently inhibited iodide uptake in a competitive manner. Electrophysiological characteristics were examined using the whole-cell patch-clamp technique. The holding current at-40 mV rapidly shifted inwardly when the cells were perfused with 1 mEq I- or SCN-. The inward current induced by 1 mEq I- did not increase when bathing solution was replaced with a Tyrode solution with 10 mEq I-, indicating that 1 mEq I- was a saturating amount. The inward current induced by 1 mEq I- increased 1.5-fold by changing the bathing solution to a Tyrode solution containing 1 mEq I- and 1 mEq SCN-. The inward current induced by 0.5 mEq SCN- decreased when the bathing solution was changed to a Tyrode solution containing 0.5 mEq SCN- and 10 mEq I-. These findings indicated that the I- ion and the SCN- ion were carried by the NA+/ I- symporter with at least two Na+ ions. The current induced by the transport of SCN- was larger than that induced by the transport of I-, possibly because the number of Na+ ions that was carried with one SCN- ion was larger than the number of Na+ ions carried with one I- ion. Surprisingly, the perfusion of ClO-4 did not induce an inward current, indicating that ClO-4 bound to the Na+/I- symporter, but was not carried by it, or that one ClO-4 ion was carried with one Na+ ion.

Animals↗
PubMed1997

PCF1 and PCF2 specifically bind to cis elements in the rice proliferating cell nuclear antigen gene.

We have previously defined the promoter elements, sites IIa and IIb, in the rice proliferating cell nuclear antigen (PCNA) gene that are essential for meristematic tissue-specific expression. In this study, we isolated and characterized cDNAs encoding proteins that specifically bind to sites IIa and IIb. The two DNA binding proteins, designated PCF1 and PCF2, share > 70% homology in common conserved sequences at the N-terminal regions. The conserved regions are responsible for DNA binding and homodimer and heterodimer formation, and they contain a putative basic helix-loop-helix (bHLH) motif. The structure and DNA binding specificity of the bHLH motif are distinguishable from those of other known bHLH proteins that bind to the E-box. The motif is > 70% homologous to several expressed sequence tags from Arabidopsis and rice, suggesting that PCF1 and PCF2 are members of a novel family of proteins that are conserved in monocotyledons and dicotyledons. A supershift assay using an anti-PCF2 antibody showed the involvement of PCF2 in site IIa (site IIb) binding activities in rice nuclear extracts, particularly in meristematic tissues. PCF1 and PCF2 were also more likely to form heterodimers than homodimers. Our results suggest that PCF1 and PCF2 are involved in meristematic tissue-specific expression of the rice PCNA gene through binding to sites IIa and IIb and formation of homodimers or heterodimers.

Amino Acid Sequence↗