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S Kosugi

Publications and source records attributed to S Kosugi.

At least 73 records · Page 4Linked to original sources
PubMed1997

Telomerase activity and metastasis: expansion of cells having higher telomerase activity within culture lines and tumor tissues.

Tumor cells with metastatic potential may have a high telomerase activity that augments telomeric DNA repeats, allowing the cells to escape from the inhibition of cell proliferation due to shortened telomeres. We examined the expression level of telomerase activity using the telomeric repeat amplification protocol among a series of cell lines obtained by repeated transplantation of a mouse fibrosarcoma. The lines could be grouped into three; one has no metastatic potential, and the other two show metastatic abilities after intravenous or subcutaneous injection. Comparison of their telomerase activity indicated that more malignant lines had higher activity. A similar relation was seen in metastatic nodules formed through clonal expansion from the heterogeneous population of inoculated cells; clonality was monitored in terms of variable patterns of subtelomeric repeats. The results suggest that a high level of telomerase activity may not be requisite for metastasis, but may confer a propensity to dominate in a tumor tissue.

Animals↗
PubMed1997

Platelet-associated IgM elevated in patients with chronic hepatitis C contains no anti-platelet autoantibodies.

We investigated whether thrombocytopenia in patients with chronic hepatitis C is due to anti-platelet autoantibodies. Platelet-associated IgG (PAIgG) and platelet-associated IgM (PAIgM) were measured by direct immunofluorescent flow cytometric analysis. Elevation of PAIgM level was detected in 70% of chronic hepatitis C patients, while only a mild elevation of PAIgG level was detected in 32% of the cases. The elevation of PAIgM values in these patients was comparable to that in patients with chronic immune thrombocytopenic purpura (ITP). However, elevated PAIgM was also found in both patients with and without thrombocytopenia, and no correlation was found between PAIgM and platelet count. Eluted PAIgM did not react with normal platelets in all cases with a positive PAIgM value, indicating that eluted PAIgM contained no detectable anti-platelet antibodies. During alpha-interferon therapy, the level of PAIgM increased in association with the decrease in platelet counts in 75% of the cases; however, eluted PAIgM at any day point never reacted with platelets from normal donors. PAIgM was elevated in patients with chronic hepatitis C, but contained no detectable anti-platelet autoantibodies. Thrombocytopenia in these patients is not due to anti-platelet autoantibodies.

Autoantibodies↗
PubMed1997

A homozygous missense mutation of the sodium/iodide symporter gene causing iodide transport defect.

Iodide transport defect is a disorder characterized by an inability of the thyroid to maintain an iodide concentration difference between the plasma and the thyroid. The recent cloning of the sodium/iodide symporter (NIS) gene enabled us to characterize the NIS gene in this disorder. We identified a homozygous missense mutation of A-->C at nucleotide +1060 in NIS complementary DNA in a male patient who was born from consanguineous marriage, had a huge goiter, and lacked the ability to accumulate iodide but was essentially euthyroid. The mutation results in an amino acid replacement of Thr354-->Pro in the middle of the ninth transmembrane domain. COS-7 cells transfected with the mutant NIS complementary DNA showed markedly decreased iodide uptake, confirming that this mutation was the direct cause of the disorder in the patient. Northern analysis of thyroid ribonucleic acid revealed that NIS messenger ribonucleic acid level was markedly increased (> 100-fold) compared with that in the normal thyroid, suggesting possible compensation by overexpression.

Amino Acid Sequence↗
PubMed1997

Recent trends in the management of Graves' hyperthyroidism in Japan: opinion survey results, especially on the combination therapy of antithyroid drug and thyroid hormone.

An opinion survey concerning the management of Graves' hyperthyroidism was conducted among the council members of the Japan Thyroid Association. The selection of 3 major treatments by 90 respondents for their patients was 98.6 +/- 4.2% for antithyroid drug (ATD), 7.8 +/- 12.6% for partial thyroidectomy and 5.2 +/- 8.1% for radioiodide. They expressed a movement away from the past trend of surgery because of postoperative complications and unsatisfactory therapeutic results, and they assumed a further reduction in the future. On the other hand, the frequency of radioiodide treatment was not considered to have decreased greatly, and they expected a slight increase in the future. Of the respondents, 65% suggested that hyperthyroidism should be completely cured even if the patient would fall into hypothyroidism. The major reasons for choosing surgery or radioiodide after ATD were the adverse effects of ATD and the age and social backgrounds of the patients. Large goiter size was the 3rd reason for surgery but was a minimal indicator for radioiodide. As for ATD treatment, none of the respondents reported the routine application of any uniform fixed-time therapy protocol. Japanese Graves' patients were shown to be less responsive to ATD than Caucasian patients. This was assumed to result at least from high iodide intake, and half of them had ordered their patients to restrict iodide intake. Furthermore, 78% of them had treated with a combined therapy of ATD and thyroid hormone. Most of them apply this for selected patients mainly to lower TSH receptor antibody activity, to better control their patients and to reduce the goiter size. All but 8 (9%) did not give T4 (or T3) after the cessation of ATD, and they felt this to be unnecessary, doubtful about the effect, unsuitable or even possible to induce recurrence. The excellent findings reported by Hashizume et al. (N Engl J Med 324: 947-953, 1991) are well known among them. However, most of them did not agree with the efficacy of the protocol to reduce TRAb or to improve the remission rate, and 90% of the respondents did not intend to apply the protocol immediately. In conclusion, the Japanese thyroidologists were shown to highly prefer ATD, and they intended to treat their patients for longer periods of time only by ATD until clinical remission is achieved. The combination therapy is widely used, but most of them do not consider it effective. The therapeutic protocol reported by Hashizume et al. was not accepted widely in Japan.

Antithyroid Agents↗
PubMed1997

Effectiveness of a short-term steroid treatment on the reduction in goiter size in antithyroid drug-treated patients with Graves' disease.

Reduction of goiter size is one of the criteria necessary to determine clinical remission in antithyroid drug (ATD)-treated Graves' patients. To facilitate goiter reduction or to achieve quick remission, a short-term steroid treatment was administered to 5 Graves' patients. These patients had been treated with ATD for a considerable period of time, had maintained euthyroidism with negative or weak thyrotropin-binding inhibitor immunoglobulin (TBII), but still had an enlarged goiter and remained T3 unsuppressive. Betamethazone was initially given 1.5 mg daily and then gradually tapered to 0 mg for 3 months. Compared to the 6-month observation period or the pre-medication period, goiter reduction exceeding 0.7 cm was achieved in all 5 patients during the steroid treatment. These reductions partly reversed to an extent smaller than pre-treatment levels in 2 patients, but continuous goiter reductions were observed for at least 3 months after steroid cessation in 3 patients. In 2 of these reduced goiter patients, T3 suppressibility was confirmed, and they were diagnosed in remission. During steroid administration, serum T3 and TSH concentrations were lowered but reversed shortly, serum fT4 concentrations did not change, and TBII levels became negative in all patients including the 2 with weak positive values before the treatment. In conclusion, a short-term steroid treatment for goitrous ATD-treated Graves' patients appears promising in achieving goiter reduction or remission.

Adult↗
PubMed1997

[AIDS counseling].

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Acquired Immunodeficiency Syndrome↗
PubMed1997

[TSH receptor].

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Humans↗
PubMed1997

[Detection of anti-GPIIb-IIIa autoantibodies and its clinical significance in autoimmune thrombocytopenic purpura].

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by thrombocytopenia due to antiplatelet autoantibodies. It has been demonstrated that the platelet glycoprotein (GP) IIb-IIIa and/or GPIb-IX are major target antigens for the autoantibodies in this disorder. Diagnosis of ITP has usually been based on clinical criteria. However, development of reliable immunological techniques enable us to make a diagnosis of "autoimmune thrombocytopenic purpura" in some patients. In this paper, we review the immunological techniques such as immunoblot assay, immunoprecipitation assay, and modified antigen capture ELISA, and discuss the clinical significance of the detected anti-GPIIb-IIIa auto-antibodies.

Autoantibodies↗
PubMed1996

The role of Asp578 in maintaining the inactive conformation of the human lutropin/choriogonadotropin receptor.

A constitutively activating mutation encoding Asp578-->Gly in transmembrane helix 6 of the lutropin/choriogonadotropin receptor (LHR) is the most common cause of gonadotropin-independent, male-limited precocious puberty. This mutant LHR produces a 4.5-fold increase in basal cAMP when expressed in COS-7 cells. To better understand the normal role of Asp578 in the LHR we studied the effect of seven other amino acid substitutions at this position. No agonist binding or response was detected with the Asp578-->Pro mutant. Agonist binding affinity was unaffected by the other substitutions and estimated receptor concentrations ranged from 11 to 184% of wild type. Substitution of Asp578 with Asn, a similarly sized, uncharged residue, did not produce agonist-independent activation. In contrast, replacement with Glu, Ser, or Leu caused 4. 9-5.6-fold stimulation of basal cAMP. Substitution with Tyr (8.5-fold) or Phe (7.5-fold) had a greater activating effect. Only the Tyr, Phe, and Leu mutants showed constitutive activation of the inositol phosphate pathway. Our data suggest that it is the ability of the Asp578 side chain to serve as a properly positioned hydrogen bond acceptor, rather than its negative charge, that is important for stabilizing the inactive state of the LHR. A bulky aromatic side chain at position 578 may further destabilize the inactive receptor conformation.

Animals↗
PubMed1996

Establishment and characterization of a Chinese hamster ovary cell line, CHO-4J, stably expressing a number of Na+/I- symporters.

The cDNA of the Na+/I- symporter playing a key role in thyroid iodide transport was cloned very recently. To characterize its function, we transfected the Na+/I- symporter gene into Chinese hamster ovary (CHO) cells and established a cell line stably expressing a number of rat Na+/I- symporters, named CHO-4J. Iodide uptake was dependent on [Na+] and reached a plateau within 30 min. Kinetic studies revealed that the K(m) for iodide was 35 microM, similar to that of FRTL-5 thyroid cells. The maximal velocity (Vmax) at cell protein level was 6-10-fold higher than in FRTL-5 cells and that at single cell level was approximately 1000-fold higher. CIO4- and SCN- dose-dependently inhibited iodide uptake in a competitive manner. The Ki was 1.5 and 16 microM, respectively. Iodide efflux from CHO-4J cells was apparently slower (t1/2 = 15 min) than FRTL-5 cells (t/2 = 2 min). Electrophysiological characteristics were examined using the whole cell patch clamp technique. Rapid inward current was observed when CHO-4J cells were perfused with 50-1000 microM Nal, suggesting a transport stoichiometry of at least 2 Na+ per I-. The current-voltage relation revealed that this current was membrane potential-dependent. The reversal potential was very close to that of Na+ in agreement with dependency on the Na+ electrochemical gradient. CHO-4J cells with a slow iodide efflux, expressing a number of Na+/I-symporters whose characteristics are identical to those of FRTL-5 cells will function as a new tool for sensitive of iodide uptake.

Animals↗
PubMed1996

Affinity modulation of the platelet integrin alpha IIb beta 3 by alpha-chymotrypsin: a possible role for Na+/Ca2+ exchanger.

In the present study, we have investigated the mechanism of affinity modulation of alpha IIb beta 3 by chymotrypsin. We first confirmed that alpha-chymotrypsin could activate alpha IIb beta 3 (approximately 7,000 molecules per platelet) without major intracellular signaling. However, we unexpectedly found that high concentrations of amiloride dose-dependently inhibited 125I-fibrinogen binding to the chymotrypsin-treated platelets, as well as the platelet aggregation (IC50 [50% inhibitory concentration] for fibrinogen binding, 530 mumol/L). In contrast, amiloride did not inhibit alpha IIb beta 3 activation induced by anti-alpha IIb beta 3 monoclonal antibody PT25-2 or AP5. To identify the pathway involved, the effects of alteration of Na+ gradient in platelets were examined. Lowering Na+ gradient by replacing extracellular Na+ with tetramethylammonium (TMA) increased the number of activated alpha IIb beta 3 by twofold, as assessed by fibrinogen-binding assay. The incubation of platelets with ouabain, a Na+/K(+)-adenosine triphosphatase (ATPase) inhibitor, further augmented alpha IIb beta 3 activation. These data suggested that a likely candidate for the pathway was Na+/Ca2+ exchanger. At 140 mmol/L [Na+]o, 45Ca2+ influx to the chymotrypsin-treated platelets was twofold greater than that to non-treated platelets. Replacement of Na+ with TMA further increased the Ca2+ influx, and the increase was inhibited by amiloride dose-dependently. 3',4'-Dichlorobenzamil (DCB) and bepridil, relatively specific inhibitors of Na+/Ca2+ exchanger, also inhibited the chymotrypsin-induced alpha IIb beta 3 activation, and the IC50 values of these inhibitors for fibrinogen binding were 25 mumol/L and 52 mumol/L, respectively. Moreover, platelet aggregation induced by various physiologic agonists was inhibited by DCB or bepridil, while platelet agglutination by ristocetin was not. Our data newly suggest that Na+/Ca2+ exchanger operating in reverse mode may be directly involved in inside-out signaling that activates alpha IIb beta 3.

Amiloride↗
PubMed1996

Constitutive activation of the thyrotropin receptor by mutating CYS-636 in the sixth transmembrane segment.

The rat thyrotropin receptor (TSHR) has 7 Cys residues in its transmembrane (TM) segments. We investigated the roles of these Cys residues by individually mutating each to Ser, transfecting the mutant DNA into Cos-7 cells and measuring TSH binding and cAMP/phosphoinositide (PIP2) responses to TSH and Graves' IgGs. Mutation of Cys-636 in the 6th TM helix to Ser markedly increased cAMP level without stimulation. Constitutive activation by this mutation contributes to a more complete map for activating TSHR mutation. Mutation of other Cys residues partially impaired responses but no mutants showed complete loss of receptor function, indicating that these residues have no major contribution to the overall 3-D structure of the TSHR.

Animals↗
PubMed1996

Cysteine-699, a possible palmitoylation site of the thyrotropin receptor, is not crucial for cAMP or phosphoinositide signaling but is necessary for full surface expression.

We investigated the role of the cysteine residues in the cytoplasmic tail of the thyrotropin receptor (TSHR) in TSH binding and signal transduction by individually mutating two cysteine residues to serine. Neither mutant exhibited changes in basal, TSH- or Graves' IgG-stimulated cAMP or inositol phosphate responses. However, mutation of Cys-699 significantly decreased TSH binding Bmax without significantly changing binding affinity, amount or sizes of TSHR forms on Western blots. These findings suggest that Cys-699, which is a potential site for lipid modification and whose equivalent in other receptors was shown to be palmitoylated, is important for efficiency of proper membrane insertion and/or stability of the receptor.

Amino Acid Sequence↗
PubMed1996

Circulating thrombopoietin level in chronic immune thrombocytopenic purpura.

The circulating thrombopoietin (TPO) level in 43 patients with chronic immune thrombocytopenic purpura (ITP) was examined by an ELISA system. The TPO level (mean +/- SD) in ITP patients was mildly elevated (1.86 +/- 1.17 fmol/ml) compared to that in normal subjects (0.76 +/- 0.21), and was within the normal range in 30% of ITP patients. In contrast, the TPO level in patients with aplastic anaemia was very high, 12.35 +/- 6.42 fmol/ml. There was no correlation between TPO level and platelet count in ITP patients. Splenectomy was performed in two ITP patients, after which platelet counts increased to normal levels and TPO levels showed a transient increase. These data suggest that reactive TPO production against thrombocytopenia in ITP is small when compared to that in aplastic anaemia. Relative endogenous TPO deficiency may play some role in the pathophysiology of thrombocytopenia in ITP patients.

Adult↗
PubMed1996

A single nucleotide insertion in codon 317 of the CD36 gene leads to CD36 deficiency.

CD36 is a multifunctional integral-membrane glycoprotein that acts as a receptor for thrombospondin, collagen, long-chain fatty acids, and oxidized LDL. Platelet CD36 deficiency can be divided into two groups. In type I, neither platelets nor monocytes/macrophages express CD36; in type II, monocytes/macrophages express CD36 but platelets do not. Two known mutations cause CD36 deficiency, ie, a 478C-->T substitution in codon 90 (proline90-->serine) and a dinucleotide deletion at nucleotide 539 in codon 110. In this study we investigated a type I Japanese subject (A.T.) and identified a new mutation, a single nucleotide insertion at nucleotide 1159 in codon 317. This mutation leads to a frameshift and the appearance of a premature stop codon. CD36 gene analysis indicated that A.T. was a compound heterozygote for a dinucleotide deletion at nucleotide 539 and the single nucleotide insertion at nucleotide 1159. RNase protection studies suggested that the new mutation as well as the dinucleotide deletion led to a marked reduction in the level of CD36 mRNA in her macrophages. However, the new mutation could be detected in macrophage but not platelet CD36 mRNA. These data suggest that the allele having the single nucleotide insertion in this subject has an additional abnormality that results in the absence of the mutated CD36 mRNA in platelets.

Base Sequence↗
PubMed1996

Laboratory tests necessary at the first examination of patients with suspected thyroid disorders.

In order to determine what and how many test items are necessary for the initial tests when examining patients with thyroid disorders, a questionnaire was sent to the council members of the Japan Thyroid Association. Thyroid disorders were divided into 4 categories; hyperthyroidism, hypothyroidism, diffuse goiter, and nodular goiter. The questionnaire was designed to assess: 1) tests routinely ordered at the initial examination; 2) minimum test battery necessary; 3) the 5 most important tests in order; and 4) selection of only 2 tests at most. The data on 112 completed questionnaires were collected and analyzed. When the choice was limited to only 2 tests, TSH and fT4 were commonly selected for hyperthyroidism hypothyroidism and diffuse goiter, but these 2 tests would be insufficient for the differentiation of disorders. In the case of nodular goiter, ultrasonogram and fine needle aspiration biopsy (FNA) were selected. The mean number of routinely ordered tests was 6.62 +/- 2.00 (S.D.) for hypothyroidism and 8.06 +/- 2.48 for nodular goiter, but many fewer tests were cited as absolutely necessary. In hyperthyroidism, 4.56 +/- 1.92 tests were required, in hypothyroidism 4.39 +/- 1.92, in diffuse goiter 4.93 +/- 1.75, and in nodular goiter 5.15 +/- 2.13. Most of the function-related tests, ultrasonogram and autoantibodies were commonly selected, while TBII and thyroid 123I or 99mTcO4 uptake in hyperthyroidism, and FNA, Tg and scintigram in nodular goiter were considered to be for specific purposes. Summarizing all these, the authors propose 5 or 6 tests to be necessary as the initial tests when examining patients with 4 individual thyroid disorders.

Autoantibodies↗
PubMed1996

Platelet-associated anti-glycoprotein (GP) IIb-IIIa autoantibodies in chronic immune thrombocytopenic purpura mainly recognize cation-dependent conformations: comparison with the epitopes of serum autoantibodies.

Platelet-associated and serum anti-glycoprotein (GP) IIb-IIIa autoantibodies were investigated in 57 patients with chronic immune thrombocytopenic purpura (ITP). In modified antigen capture ELISA (MACE) using GPIIb-IIIa-specific-, GPIIb-specific-, and GPIIIa-specific-monoclonal antibody (mAb) for antigen capture, platelet-associated anti-GPIIb-IIIa antibodies were detected in 14 out of 37 patients (38%), and these antibodies could be detected with all 3 mAbs used for antigen capture. In the MACE using EDTA-treated platelets at 37 degrees C, the reactivity of platelet-associated anti-GPIIb-IIIa antibodies in 9 out of 10 patients was markedly reduced in both cases of GPIIb-specific- and GPIIIa-specific-mAb used. Immunoprecipitation experiments further confirmed that the EDTA-treatment abrogated the antigenicity of GPIIb-IIIa for platelet-associated antibodies in 2 patients. Serum anti-GPIIb-IIIa autoantibodies were detected in 23 out of 57 patients (40%). However, only 7 out of 23 serum anti-GPIIb-IIIa antibodies could be detected with all 3 mAbs. The MACE using EDTA-treated platelets further showed that the features of serum anti-GPIIb-IIIa antibodies were different from those of platelet-associated antibodies even in the same patient. Our data demonstrate that the platelet-associated anti-GPIIb-IIIa antibodies mainly recognize the cation-dependent antigenic determinants on GPIIb-IIIa and that serum anti-GPIIb-IIIa antibodies may contain some components which differ in specificity from platelet-associated antibodies.

Antibodies, Monoclonal↗