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S Kosugi

Publications and source records attributed to S Kosugi.

At least 37 records · Page 2Linked to original sources
PubMed2000

Clinical features of multiple endocrine neoplasia type 1 (MEN1) phenocopy without germline MEN1 gene mutations: analysis of 20 Japanese sporadic cases with MEN1.

OBJECTIVE: Multiple endocrine neoplasia type 1 (MEN1) is a familial tumour syndrome of endocrine tumours involving parathyroids, anterior pituitary and enteropancreatic neuroendocrine tissues, and is inherited in an autosomal dominant manner with high penetrance. Recently, the gene responsible for this syndrome, MEN1, was positionally cloned from chromosome 11q13. PATIENTS: To characterize sporadic MEN1 patients, we analysed the MEN1 gene by direct sequencing of the entire open reading frame from 20 individuals. RESULTS: We identified heterozygous germline mutations of the MEN1 gene in 8 of 20 (40%) cases. Seven were novel MEN1 germline mutations. Three mutations were splicing abnormalities, and all were confirmed to be splicing defects by RT-PCR. The clinical significance of detecting germline MEN1 mutations, not only in familial MEN1 but also in sporadic MEN1, was confirmed by the finding of asymptomatic mutant carriers among family members of the sporadic MEN1 patients. Seven of 8 cases with MEN1 mutations had enteropancreatic lesions in contrast to 4 of 12 (P < 0.018) in those cases with no mutation. Ten of the 12 cases without MEN1 mutation were more than 50-year-old. Six of these 10 cases had the same clinical features; primary hyperparathyroidism and a GH-secreting pituitary tumour. CONCLUSIONS: It is likely that the six cases without mutations were MEN1 phenocopies due to (i) two kinds of tumours with high natural incidence in older subjects developed by chance (ii) another familial tumour syndrome with low penetrance, e. g. familial acromegaly with primary hyperparathyroidism by mutation of another gene, or (iii) somatic mutation during early embryonic stages.

Adult↗
PubMed2000

Hyperthyroid Graves' disease after hemithyroidectomy for papillary carcinoma: report of three cases.

Here we report three cases of hyperthyroid Graves' disease that occurred after partial thyroidectomy for papillary carcinoma. In Case 1, the patient first developed hyperthyroidism 2 years after resection of left thyroid lobe, was treated for 2 years with antithyroid drug which was then discontinued, and relapsed with periodic paralysis after 8 years of remission. In Case 2, a hyperfunctioning remnant thyroid was noted 22 years after right hemithyroidectomy. In Case 3, where thyrotoxic symptoms became evident 7 weeks after right hemithyroidectomy, autoantibodies to thyroglobulin and thyroid microsome were positive in preoperative serum, in line with a report by others detecting these antibodies in 2 out of 3 such cases examined. Later bioassay revealed activity of thyroid stimulating antibodies in that serum, with further increase in titer in the sample taken at the clinical manifestation. Hence in Case 3, surgical stress may have altered immunological homeostasis, promoting a preclinical Graves' disease to full-blown hyperthyroidism.

Adult↗
PubMed2000

A novel activating mutation in the thyrotropin receptor gene in an autonomously functioning thyroid nodule developed by a Japanese patient.

OBJECTIVE: A number of activating mutations of the thyrotropin receptor (TSHR) have been found in autonomously functioning thyroid nodules (AFTNs) in European patients. We aimed to study TSHR mutation in AFTNs in Japanese patients because no TSHR activating mutation has been found by previous incomplete studies. DESIGN: A typical AFTN developed in a 69-year-old Japanese woman was studied. METHODS: The entire exon 10 of the TSHR cDNA was sequenced. Functional studies were done by site-directed mutagenesis and transfection of a mutant construct into COS-7 cells. RESULTS: We identified a novel heterozygous TSHR gene mutation, Leu512-->Arg (L512R; CTG-->CCG), from the AFTN. The mutation was not detected in the adjacent normal thyroid tissue. COS-7 cells transfected with L512R mutant TSHR expression vector exhibited a 3.3-fold increase in basal cAMP level compared with that of cells transfected with wild-type TSHR DNA, confirming that the mutation was the direct cause of the AFTN. TSHR activating mutations involving the third transmembrane helix reported to date are S505R/N and V509A as well as L512R. An in vitro site-directed mutagenesis study encompassing residues 505-513 revealed that mutations involving residues other than these three did not show constitutive activation. CONCLUSION: This is the first TSHR activating mutation found in a Japanese patient, although true prevalence of TSHR activating mutations in AFTNs developed in Japanese patients remains to be elucidated. In addition, functional studies suggested that amino acid residues in the third transmembrane helix maintaining inactive conformation of the TSHR seem to be located on the same surface of the alpha-helix, possibly making interhelical bonds with another helix.

Aged↗
PubMed2000

Effects of social support and self-esteem on depressive symptoms in Japanese middle-aged and elderly people.

We examined the relationship among social support, self-esteem, and depression. The subjects were 1,116 Japanese community-dwelling adults aged between 40-79, who were the first wave participants of the National Institute for Longevity Sciences--Longitudinal Study of Aging (NILS-LSA). Exploratory and confirmatory factor analyses were performed on the Rosenberg's self-esteem scale that supported the superiority of the bi-dimensional structure of the scale marked by self-confidence and self-deprecation subscales. The subsequent causal analyses, using structural equation modeling, demonstrated that social support reduced depressed affect through an increase in self-confidence and a decrease in self-deprecation. By contrast, social support did not show a direct effect on depressed affect. The findings suggest the importance of esteem-improving elements of social support in reducing depressive symptoms.

Adult↗
PubMed2000

[Clinical Genetics Network(Idennet) as a back-up system for clinical management of hereditary tumors].

We, Clinical Genetics Unit, Kyoto University Hospital, have established an internet homepage, Clinical Genetics Network(Idennet)(URL: http:¿www.kuhp.kyoto-u.ac.jp/idennet) to provide various information necessary for genetics clinics. One of the most important contents is the "Online Database of Gene Tests" which provides real time information on gene tests performed at research facilities such as universities and available for outsiders. The point of this database is direct input of information by registered users, making information always updated. 46 gene tests for hereditary tumors have been registered in the "Online Database of Gene Tests". This database will be a useful tool for clinical management of patients and family members with hereditary tumors.

Databases, Factual↗
PubMed2000

Establishment and characterization of a breast cancer cell line expressing Na+/I- symporters for radioiodide concentrator gene therapy.

UNLABELLED: 131I therapy is a widely accepted treatment for metastatic differentiated thyroid cancer. To investigate the feasibility of 131I therapy for breast cancer, we established breast cancer cells stably expressing Na-/I- symporter (NIS) gene that can be modulated and studied in vitro and in vivo. METHODS: We transfected rat NIS genes into a human breast cancer cell line (MCF7) by electroporation. Iodide accumulation was evaluated under various extracellular concentrations of sodium and iodide, and iodide efflux was also assessed. Biodistribution and tumor imaging were studied using tumor-bearing mice. RESULTS: A novel cell line (MCF3B), stably expressing the NIS gene, was established from MCF7. MCF3B took up 44 times more radioiodide in vitro than MCF7 did. Iodide uptake was completely inhibited by 1 mmol/L perchlorate and was dependent on external sodium and iodide concentrations. Iodide efflux from MCF3B cells was slower (half-life [T 1/2] > 27 min) than from FRTL5 thyroid cells (T 1/2 = 4 min). In the biodistribution study using MCF3B-xenografted mice, high tumor uptake of 125I was shown (16.73%) at 1 h after injection, and tumor-to-normal tissue ratios were also high (4.84-21.28), except in the stomach (0.47). However, the iodide accumulation in the tumor lessened with time, reaching less than 1% at 24 h after injection. CONCLUSION: Our preliminary data indicate that NIS-based gene therapy may be applied by concentrating a lethal dose of radiation in tumor cells in vivo, but further investigation is necessary to determine a method of maintaining radioiodine in the cells to allow greater therapeutic effects.

Animals↗
PubMed1999

Homozygous deletions and point mutations of the Ikaros gene in gamma-ray-induced mouse thymic lymphomas.

Our previous genome-wide analysis of allelic loss for thymic lymphomas that were induced by gamma-irradiation in F1 hybrid mice between BALB/c and MSM strains suggested the centromeric region on chromosome 11 as a site harboring a tumor suppressor gene. Interestingly, to this region the mouse Ikaros gene was mapped which was postulated to participate in oncogenic process from the study of Ikaros knockout mice. Here we show fine allelic loss mapping in the vicinity of Ikaros in 191 lymphomas, indicating that the critical region of allelic loss was centered at the Ikaros locus. PCR analysis revealed that nine lymphomas failed to give PCR-amplification for either of two exon primer pairs, indicative of homozygous deletion. Six and five mutations were detected in the N-terminal zinc finger domain and the activation domain of Ikaros, respectively, and six of the eleven were frameshift or nonsense mutations that resulted in truncation of Ikaros protein. The results strongly suggest a direct role for Ikaros in development of mouse thymic lymphomas. This provides the experimental basis for further analysis of Ikaros mutations in human cancer.

Animals↗
PubMed1999

Allelic loss mapping and physical delineation of a region harboring a putative thymic lymphoma suppressor gene on mouse chromosome 12.

Our previous allelic loss analysis of gamma-ray induced thymic lymphomas in F1 hybrid and backcross mice between BALB/c and MSM strains mapped the Tlsr4 region exhibiting a high frequency of allelic loss (62%) to a 2.9 cM interval between the markers D12Mit53 and D12Mit279 on mouse chromosome 12. To narrow further the interval harboring a putative tumor suppressor gene, a high-density scan has been carried out for informative 361 thymic lymphomas. Construction of a physical map of Tlsr4 with 3 YAC and 15 BAC clones and isolation of YAC- and BAC-derived polymorphic probes lead to fine allelic loss mapping. Three successive polymorphic sites within one BAC exhibit the retention of both alleles in seven, one and four lymphomas, suggesting that a common region of allelic loss for Tlsr4 exists within the BAC region. Pulsed-field gel electrophoresis of NotI digests of this and other clones determines that the commonly lost region is a 35 kb interval with a NotI site. NotI sites are frequently associated with coding regions, and our preliminary sequencing has identified ESTs in the region. Thus, the present study facilitates the identification of genes in the Tlsr4 region that would lead to isolation of a novel tumor suppressor gene.

Alleles↗
PubMed1999

A TSH/dibutyryl cAMP activated Cl-/I- channel in FRTL-5 cells.

An iodide (I) and chloride (Cl) channel has been identified in the continuously cultured FRTL-5 thyroid cell line using a cell attached patch clamp technique. The channel is activated by TSH and dibutyryladenosine cyclic monophosphate (Bt2-cAMP) but not by phorbol 12-myristate 13-acetate (TPA). Gluconate can not replace chloride or iodide and the channel is impermeable to Na+,K+ and tetraethylammonium ions. The current-voltage relationship demonstrates that the single channel current is a linear function of the clamp voltage. Single channel currents reversed at a pipette potential close to 0 mV. The mean single channel conductance was 60 pS for Cl- and 50 pS for I-. From the I-V relationship there was a strong outward rectification with Cl-, and a complete block with I-, in the single channel current above +40 mV. The feature of the channel is manifested in the single channel records by four distinct, equally spaced conductance levels. We suggest the channel is important for the transport of I and Cl ions across the apical membrane into the colloid space and is important for hormone synthesis and follicle formation.

Animals↗
PubMed1999

Mutations in the p53 and scid genes do not cooperate in lymphomagenesis in doubly heterozygous mice.

Analysis of double mutant mice of the p53 and scid genes, which have a combination of cell cycle checkpoint/apoptosis and DNA repair defects, shows that the latter defect synergistically enhances lymphoma development with loss of the former function. These mice lack the ability to eliminate lymphocytes predisposed to neoplastic transformation resulting from faulty antigen receptor gene rearrangement. Here we examine the cooperativity in double heterozygotes of p53 and scid in which normal development of lymphocytes is not impaired. MSM mice carrying a p53-knockout allele were crossed with BALB/c mice heterozygous for the scid locus and 129 offspring were obtained. They were subjected to gamma-ray irradiation, 84 thymic lymphomas being generated. The tumors and host mice were genotyped of p53 and scid. Among 42 mice developing p53-deficient lymphomas, scid/+ and +/+ genotypes did not provide difference in onset and latency. Besides, allelic loss of the Scid gene occurred at a high frequency in those lymphomas but the loss exhibited no allelic bias. The results suggest that the scid/+ genotype is not a modifier of loss of p53 function in the double heterozygotes.

Alleles↗
PubMed1999

Accumulation of recombinant chromosomes and low fidelity of transmission of chromosome X DNA markers in gamma-ray-induced lymphomas lacking p53.

F1 offspring of male MSM male mice with a p53-deficient (knockout) allele and normal female BALB/c mice were backcrossed with MSM mice to produce N2 mice. Female F1 and N2 mice were irradiated with gamma-radiation, and thymic lymphomas were obtained from 69 F1 and 82 N2 mice heterozygous for X chromosome markers. Of these 151 mice, 91 carried a p53-deficient allele. These lymphomas were analyzed for allelic loss by using four marker loci distributed on X chromosome to assess the stability of the inactive X chromosome, which contributes little to cellular functions. Twenty lymphomas showed allelic loss of all four loci, suggesting loss of a whole inactive X chromosome due to mitotic nondisjunction, whereas 24 lost only a part of an X chromosome, as a result of somatic recombination. The p53 status of the lymphomas was determined by genotyping and allelic loss analysis: 53 had retained two wild-type p53 alleles, suggesting normal function; 69 had lost both alleles, indicating loss of function; and the remaining 29 had at least one wild-type p53 allele, so their p53 status was unclear. Compilation of these two data revealed one nondisjunction-type change and five recombination-type mutations on X chromosome in 53 lymphomas retaining functional p53. In contrast, 14 and 16 of these alterations, respectively, were observed in 69 lymphomas lacking p53 function. These results suggest that p53 loss significantly increases the accumulation of recombinant chromosomes and decreases the fidelity of mitotic chromosome transmission of the X chromosome in gamma-ray-induced lymphomas.

Animals↗
PubMed1999

Two germline missense mutations at codons 804 and 806 of the RET proto-oncogene in the same allele in a patient with multiple endocrine neoplasia type 2B without codon 918 mutation.

Multiple endocrine neoplasia (MEN) type 2B is a clinically distinct entity among the autosomal dominant MEN 2 syndromes. Most patients with MEN 2B carry a germline mutation (M918T) of the RET proto-oncogene, while a few carry A883F. We examined a patient with MEN 2B, but without M918T or A883F, and her relatives. Here, we report the presence in this patient of 2 germline mutations, V804M and Y806C in the same allele. While the novel Y806C was inherited from her father, its carriers (her father and brother) was not affected by MEN 2. In contrast, V804M was a de novo mutation, that has been reported in patients with familial medullary thyroid carcinoma. Combinations of mutations of the RET proto-oncogene may cause oncogenic activities different from those of single mutations.

Base Sequence↗
PubMed1999

A novel mutation in the sodium/iodide symporter gene in the largest family with iodide transport defect.

We previously reported nine children with an autosomally recessive form of congenital hypothyroidism due to an iodide transport defect in a large Hutterite family with extensive consanguinity living in central Canada. Since the original report, we have diagnosed congenital hypothyroidism by newborn TSH screening in 9 additional children from the family. We performed direct sequencing of the PCR products of each NIS (sodium/iodide symporter) gene exon with flanking introns amplified from genomic DNA extracted from peripheral blood cells of the patients. We identified a novel NIS gene mutation, G395R (Gly395-->Arg; GGA-->AGA), in 10 patients examined in the present study. All of the parents tested were heterozygous for the mutation, suggesting that the patients were homozygous. The mutation was located in the 10th transmembrane helix. Expression experiments by transfection of the mutant NIS complimentary DNA into COS-7 cells showed no perchlorate-sensitive iodide uptake, confirming that the mutation is the direct cause of the iodide transport defect in these patients. A patient who showed an intermediate saliva/serum technetium ratio (14.0; normal, > or = 20) and was considered to have a partial or less severe defect in the previous report (IX-24) did not have a NIS gene mutation. It is now possible to use gene diagnostics of this unique NIS mutation to identify patients with congenital hypothyroidism due to an iodide transport defect in this family and to determine the carrier state of potential parents for genetic counseling and arranging rapid and early diagnosis of their infants.

Animals↗
PubMed1999

Germline MEN1 mutations in sixteen Japanese families with multiple endocrine neoplasia type 1 (MEN1).

OBJECTIVE: Multiple endocrine neoplasia type 1 (MEN1) is a syndrome of endocrine tumors involving the parathyroids, anterior pituitary and enteropancreatic neuroendocrine tissues, and is inherited in an autosomal dominant manner. Recently, the gene responsible for this syndrome, MEN1, was positionally cloned in 11q13. We aimed to assess the significance of MEN1 gene diagnostics in families with MEN1. DESIGN: Sixteen probands of familial MEN1 and their 40 family members were subjected to the study. METHODS: Full-length sequencing of the open reading frame and exon-intron boundaries in the MEN1 gene was performed with probands of familial MEN1. Family members were examined for the identified mutation in the proband. RESULTS: We identified heterozygous germline mutations of the MEN1 gene in all of 16 Japanese MEN1 families examined, achieving the highest detectability of MEN1 mutations in familial MEN1 among studies that examined more than 10 families. Eleven kinds of the identified MEN1 germline mutations were novel. More than half were nonsense or frameshift mutations resulting in a premature stop codon (9/15; 60%), and no mutation hot spots or no apparent genotype-phenotype relationships were observed, in support of the results of other studies. We identified 40 mutant MEN1 gene carriers and 16 non-carriers in the course of the present study in those families. CONCLUSIONS: Analysis of the germline mutations in the MEN1 gene, providing significantly useful clinical information to probands and family members of MEN1, should be considered as a standard procedure and categorized as belonging to Group 1 cancer predisposition testing by the American Society of Clinical Oncology.

Adult↗
PubMed1999

Laparoscopically assisted splenectomy following preoperative splenic artery embolization using contour emboli for myelofibrosis with massive splenomegaly.

Laparoscopically assisted splenectomy with an 8- to 10-cm left upper paramedian laparotomy was performed following preoperative splenic artery embolization using painless contour emboli (super absorbent polymer microsphere) with early successful results in two men (46 and 37 years old) with myelofibrosis accompanied by massive splenomegaly. Dissection around the lower part of the spleen and the hilum initially was performed intracorporeally with the usual laparoscopic view under 12 mm Hg pneumoperitoneum. The alternating changes of viewpoints between the direct view through an 8- to 10-cm incision and the usual laparoscopic view with or without application of a retraction method were effective for safe hilar devascularization. Preoperative splenic artery embolization at the distal site was effective for safe dissection around the enlarged spleen. The patients did not complain of pain before operation. Preoperative painless embolization and laparoscopically assisted splenectomy with small laparotomy promotes the feasibility and safety of minimally invasive splenectomy for myelofibrosis with massive splenomegaly.

Adult↗
PubMed1998

Involvement of Na+/Ca2+ exchanger in inside-out signaling through the platelet integrin IIbbeta3.

The platelet integrin IIbbeta3 has become a new target for the treatment of pathological thrombosis. It becomes apparent that the affinity of IIbbeta3 for its ligands is dynamically regulated by inside-out signaling. However, the components that couple diverse intracellular signals to the cytoplasmic domains of IIbbeta3 remain obscure. Employing a chymotrypsin-induced IIbbeta3 activation model, we previously proposed the hypothesis that Na+/Ca2 + exchanger (NCX) may be involved in inside-out signaling (Shiraga et al: Blood 88:2594, 1996). In the present study, employing two unrelated Na+/Ca2+ exchange inhibitors, 3',4'-dichlorobenzamil (DCB) and bepridil, we investigated the role of NCX in platelet activation induced by various agonists in detail. Both inhibitors abolished platelet aggregation induced by all agonists examined via the inhibition of IIbbeta3 activation. Moreover, these inhibitors abolished IIbbeta3 activation induced by phorbol 12-myristate 13-acetate or A23187. On the other hand, neither of these inhibitors showed apparent inhibitory effects on protein phosphorylation of pleckstrin or myosin light chain, or an increase in intracellular calcium ion concentrations evoked by 0.1 U/mL thrombin. These effects of the NCX inhibitors are in striking contrast to those of protein kinase C inhibitor, Ro31-8220. Biochemical and ultrastructural analyses showed that NCX inhibitors, particularly DCB, made platelets "thrombasthenic". These findings suggest that the NCX is involved in the common steps of inside-out signaling through integrin IIbbeta3.

Amiloride↗
PubMed1998

Differences in the electrophysiological response to I- and the inhibitory anions SCN- and ClO-4, studied in FRTL-5 cells.

The electrophysiological properties of the Na+/I- symporter (NIS) were examined in a cloned rat thyroid cell line (FRTL-5) using the whole-cell patch-clamp technique. When the holding potential was between -40 mV and -80 mV, 1 mM NaI and NaSCN induced an immediate inward current which was greater with SCN- than with I-. The reversal potential for I- and SCN- induced membrane currents was +50 mV. This is close to the value of +55 mV calculated by the Nernst equation for Na+. These results are consistent with I- and SCN- translocation via the NIS that is energized by the electrochemical gradient of Na+ and coupled to the transport of two or more Na+. There was no change in the membrane current recording with ClO-4 indicating that ClO-4 was either not transported into the cell, or the translocation was electroneutral. ClO-4 addition, however, did reverse the inward currents induced by I- or SCN-. These effects of I-, SCN- and ClO-4 on membrane currents reflect endogenous NIS activity since the responses duplicated those seen in CHO cells transfected with NIS. There were additional currents elicited by SCN- in FRTL-5 cells under certain conditions. For example at holding potentials of 0 and +30 mV, 1 mM SCN- produced an increasingly greater outward current. This outward current was transient. In addition, when SCN- was washed off the cells a transient inward current was detected. Unlike SCN-, 1-10 mM I- had no observable effect on the membrane current at holding potentials of 0 and +30 mV. The results indicate FRTL-5 cells may have a specific SCN- translocation system in addition to the SCN- translocation by the I- porter. Differences demonstrated in current response may explain some of the complicated influx and efflux properties of I-, SCN- and ClO-4 in thyroid cells.

Animals↗