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K Nakabayashi

Publications and source records attributed to K Nakabayashi.

At least 19 recordsLinked to original sources
PubMed1999

Introduction of chromosome 7 suppresses telomerase with shortening of telomeres in a human mesothelial cell line.

Introduction of human chromosome 7 by microcell-mediated chromosome transfer induced senescence in a telomerase-positive human mesothelial cell line, MeT5A. In microcell hybrids which underwent senescence, telomerase activity was decreased before entering senescence and telomeric sequences were shortened as cell division proceeded. Concomitantly, expression of the gene encoding telomerase catalytic subunit was abolished, whereas the genes encoding the RNA component of telomerase and its associated protein TEP1 were not affected. In revertants which arose from such microcell hybrids, telomerase activity was restored and the telomeric sequences were elongated. In microcell hybrids which showed no growth arrest, telomerase activity was unaltered. These results suggest that a putative mortality gene on chromosome 7 negatively regulates the telomere maintenance mechanism in MeT5A.

Chromosomes, Human, Pair 7↗
PubMed1999

Characterization of a cDNA encoding a precursor polypeptide of a D-amino acid-containing peptide, achatin-I and localized expression of the achatin-I and fulicin genes.

Achatin-I and fulicin, isolated from the ganglia and atria of the giant land snail Achatina fulica, are a tetrapeptide and pentapeptide containing a d-Phe and d-Asn at position 2, respectively. We succeeded in cloning a cDNA encoding a precursor of achatin-I from the Achatina ganglia, revealing that the d-Phe present in achatin-I is coded by a common l-Phe codon, TTT or TTC. The deduced polypeptide was found to comprise seven repeats of the achatin sequence GFAD and one analog GFGD flanked on both sides by the typical endoproteolytic site KR. Northern blot analysis of transcripts and Southern blot analysis of reverse transcription (RT)-PCR products demonstrated that achatin-I mRNA was localized in the subesophageal ganglia, whereas expression of fulicin mRNA was detected in the atrium as well as in the subesophageal ganglia. Furthermore, localization of the achatin gene transcript in the right and left pedal ganglia compartments was shown by in situ hybridization on sections of subesophageal ganglia, whereas the fulicin transcript was observed in the right and left parietal ganglia. These data suggested that achatin-I plays an essential role in the regulation of the heart as a neurotransmitter or neurohormone through production in the pedal ganglia and transport to the atrium, whereas fulicin serves not only as a neurotransmitter or neurohormone but also as a novel atrial hormone.

Amino Acid Sequence↗
PubMed1999

The introduction of dominant-negative p53 mutants suppresses temperature shift-induced senescence in immortal human fibroblasts expressing a thermolabile SV40 large T antigen.

Immortal human fibroblasts, SVts8 cells, which express a heat-labile SV40 large T antigen, induces a senescence-like phenomenon in response to upward shift in temperature. Cells with arrested division show strong induction of senescence-associated beta-galactosidase. We examined how p53 and pRB are involved in this phenomenon since they are major targets of the T antigen. Transfection of cells with plasmids encoding the wild-type T antigen or human papilloma virus type 16 E6/E7 proteins completely abolished the arrest in cell division, a plasmid encoding the E6 protein suppressed it markedly, while a plasmid encoding E7 had no effect. Plasmids encoding dominant-negative p53 mutants also suppressed the arrest in cell division to various degrees. Upon temperature shift, p21 mRNA was upregulated 10-fold in SVts8 cells, but only slightly in clones expressing the wild-type T antigen or dominant-negative p53 mutants. These data demonstrate that p53 plays a major role in this senescence-like phenomenon.

Antigens, Polyomavirus Transforming↗
PubMed1999

Defective DNA replication and repair associated with decreases in deoxyribonucleotide pools in a mouse cell mutant with thermolabile ubiquitin-activating enzyme E1.

Upon shift-up in temperature, mouse tsFS20 mutant cells with thermolabile ubiquitin-activating enzyme E1 immediately stopped DNA replication and showed cell cycle arrest in S-phase. In contrast, when the cells were permeabilized with lysolecithin after culture at the nonpermissive temperature, they exhibited a normal level of replicative DNA synthesis in vitro. In agreement with this, intracellular pools of deoxyribonucleoside triphosphates were significantly reduced in the cells cultured at the nonpermissive temperature. Even under the permissive conditions, tsFS20 cells were more sensitive to hydroxyurea and alkylating agents, and induced less mutation than the wild-type cells. These results suggest that the ubiquitin system affects DNA replication and repair.

Animals↗
PubMed1999

Identification of clp genes expressed in senescing Arabidopsis leaves.

Clp protease is a highly selective protease in E. coli, which consists of two types of subunits, the regulatory subunit with ATPase activity, ClpA, and the catalytic subunit, ClpP. In order to examine the possible association of plant Clp protease with the degradation of protein in senescing chloroplasts, we isolated a cDNA clone for ClpC which is a plant homologue of ClpA from Arabidopsis thaliana in addition to ERD1 which we had isolated earlier [Kiyosue et al. (1993) Biochem. Biophys. Res. Commun. 196: 1214]. We also isolated a clone for the plastidic gene, clpP (pclpP) and cDNA clones for putative nuclear clpP genes (nclpP1-6). We analyzed the expression of these clp genes in Arabidopsis leaves after various dark periods and during natural senescence. The expression of erd1 was increased by dark-induced and by natural senescence, as reported earlier [Nakashima et al. (1997) Plant J. 12: 851], while that of AtclpC was decreased. Two catalytic subunits nclpPs (nclpP3 and nclpP5) showed high expression in naturally senescing leaves, but the expression of pclpP and the other nclpPs was not changed. Immunoblot analysis of chloroplast protein and in vitro import analysis demonstrated that both nucleus-encoded regulatory subunits as well as nClpP5 were localized in the chloroplast stroma. These observations suggest that chloroplast Clp protease is composed of very complicated combinations of subunits, and that ERD1, nClpP5 and pClpP have a role in the concerted degradation of protein in senescing chloroplasts.

Adenosine Triphosphatases↗
PubMed1999

Dephosphorylation of specific proteins during induction of senescence in immortal human fibroblasts expressing thermolabile SV40 T antigen.

Particular protein kinase inhibitors block a senescence-like phenomenon in SVts8 cells induced by a shift up in temperature. We characterized cellular proteins with affinity chromatography using one such inhibitor as a ligand. Two proteins of 56 and 100 kDa were found to be dephosphorylated specifically, probably due to induction of a protein phosphatase activity(s).

Aging↗
PubMed1999

Hypoalbuminemia accelerates erythrocyte membrane lipid peroxidation in chronic hemodialysis patients.

BACKGROUND: Persistent hypoalbuminemia is a long-term poor prognostic factor in chronic hemodialysis patients. PATIENTS AND METHODS: We investigated the correlation between the degree of peroxidation of erythrocyte membrane lipids, erythrocyte alpha tocopherol content, erythrocyte glutathione peroxidase activity and serum albumin concentration in twelve patients with uremia not undergoing hemodialysis and fifteen patients on maintenance hemodialysis. RESULTS: The glutathione peroxidase activity in erythrocytes was higher in patients of uremia not undergoing hemodialysis than in chronic hemodialysis patients. A significant negative correlation was observed between the erythrocyte alpha tocopherol content and the degree of erythrocyte membrane lipid peroxidation in chronic hemodialysis patients. There was a statistically significant difference in the degree of erythrocyte membrane lipid peroxidation between patients with chronic hemodialysis-associated hypoalbuminemia and chronic hemodialysis patients having normal serum albumin levels. CONCLUSION: This study suggested that serum albumin inhibits peroxidation of erythrocyte membrane lipids and that hemodialysis induces recovery of serum reductivity. We conclude that persistent hypoalbuminemia worsens the serum antioxidant activity in chronic hemodialysis patients and may contribute to increased oxidative cell damage.

Erythrocyte Membrane↗
PubMed1999

[Focal segmental glomerulosclerosis associated with type C virus hepatitis and decrement of proteinuria by interferon-alpha therapy].

Focal segmental glomerulosclerosis (FSGS) associated with type C virus (HCV) hepatitis has not been described in the literature to date. However, we experienced a 30-year-old man, who had had HCV hepatitis, developed nephrotic syndrome and was admitted to our hospital. The first renal biopsy showed FSGS which was diagnosed by light, immunofluorescent, and electron microscopic study. FSGS diagnosis was based upon the findings of focal segmental glomerular sclerosis associated with hyalinosis and foam cells, segmental deposition of IgM and C3 on glomeruli, and epithelial cell vacuolization in the Bowman's space. HCV hepatitis was treated with interferon-alpha (INF-alpha) over 6 months. The treatment brought the disappearance of not only HCV-RNA from the blood, but also the manifestation of nephrotic syndrome. Therefore, the second renal biopsy was performed, but did not reveal any great pathological improvement. Five months later after the remission, he again had an elevated HCV-RNA level and a relapse of nephrotic syndrome. He was retreated with the same therapy and achieved a second remission of nephrotic syndrome. FSGS associated with HCV hepatitis is described first and the implication of INF-therapy in the improvement of proteinuria is discussed.

Adult↗
PubMed1998

DNA topoisomerase inhibitors induce reversible senescence in normal human fibroblasts.

Inhibitors of DNA topoisomerases I and II induced arrest in cell division in normal human fibroblasts depending on cell divisions. Arrested cells showed morphology similar to those of normally senesced cells and strongly induced senescence-associated beta-galactosidase. In these cells, p16ink4a was upregulated, whereas p21waf1 or p53 was not altered. Upon removal of the inhibitors, the cells resumed growth but their cumulative population doublings were reduced dose dependently. Accelerated telomere shortening was not observed in the arrested cells. These results suggest that DNA topoisomerase inhibitors are efficient and reversible inducers of premature senescence in normal human cells.

Cellular Senescence↗
PubMed1998

Atypical Takayasu arteritis: late onset and arthritic manifestations: report of two cases.

We recently experienced two cases of Takayasu arteritis rendered atypical by late onset (over 60 years of age) of disease, involvement of distal branch arteries, and association with rheumatoid arthritis. In both cases, roentgenologic examination revealed typical appearance of the abdominal aorta and stenosis of the subclavian artery entirely compatible with Takayasu arteritis. In addition, Case 1 had occlusive lesions of the superficial femoral arteries and Case 2 manifested occlusion of the axillary artery. Laboratory findings showed increased ESR and CRP but negative HLA B52 locus. Both cases showed arthritis symptoms with swelling, pain, and tenderness in joints. Case 1 did not manifest erosive lesions and positive RA test; Case 2 showed roentgenologic erosive lesions in hand joints with positive RA test. A surgical specimen from the femoral artery of Case 1 showed lesions suggesting Takayasu arteritis. Based upon these findings, we diagnosed the two patients as having atypical Takayasu arteritis with late middle age onset and arthritic manifestations.

Anastomosis, Surgical↗
PubMed1998

Clustering of human chromosome fragments on the mouse genome by chromosome-mediated gene transfer.

Pieces of metaphase chromosomes prepared from mouse cells containing neo-tagged human chromosome 7 were transferred to mouse cells with calcium phosphate to isolate G418-resistant clones. FISH analysis revealed that the majority of them contained human DNA at a single site on their genome. These transformants contained STS markers mapped to various regions of chromosome 7. It is thus suggested that pieces of human chromosomes tend to assemble and integrate on the mouse genome.

Animals↗
PubMed1998

Release of telomeric DNA from chromosomes in immortal human cells lacking telomerase activity.

Some immortal human cell lines lack telomerase activity. These cell lines were found to contain small dispersed DNA hybridizing to TTAGGG repeats. Such DNA was located in their cytoplasm and nuclei. Normal human fibroblasts or telomerase-positive cell lines did not contain such DNA. Upon cloning and sequencing, it was shown to consist of TTAGGG repeats. When electrophoresed on neutral and alkaline agarose gels, it behaved as double-stranded and linear DNA. These results suggest that telomeric DNA is released from chromosomes in association with maintenance of telomeres in telomerase-negative cell lines.

Cell Line↗
PubMed1998

Effects of truss mattress upon sleep and bed climate.

The purpose of this study was to examine the effects of a truss mattress upon sleep and bed climate. The truss mattress which has been designed to decrease the pressure and bed climate humidity was tested. Six healthy female volunteers with a mean age of 23.3 years, served as subjects. The experiment was carried out under two conditions: a truss mattress (T) and a futon (F) (Japanese bedding). The ambient temperature and relative humidity were controlled at 19-20 degrees C, and RH 50-60% respectively. Sleep was monitored by an EEG machine and the rectal temperature, skin temperature and bed climate were also measured continuously. Subjective evaluations of bed and sleep were obtained before and after the recording sessions. No significant difference was observed in the sleep parameters and time spent in each sleep stage. Rectal temperature was significantly lower in T than F. Although there was no significant difference in bed climate over the T/F, the temperature under T/F was significantly higher in T. No significant difference was observed in subjective sleep evaluation. The subjective feeling of the mattress was significantly warmer in F than T before sleep. These results suggest that although T does not disturb the sleep parameters and the bed climate is maintained at the same level as with F, it may affect rectal temperature which can be due to low thermal insulation.

Adult↗
PubMed1998

[Clinical study on five myeloperoxidase specific anti-neutrophil cytoplasmic antibody (MPO-ANCA) positive Churg-Strauss syndrome cases].

OBJECTIVE: In order to clarify the clinical characteristics of ANCA positive Churg-Strauss syndrome (CSS), ten CSS patients were analyzed. METHODS: ANCA was detected using an immunofluorescence (IF) assay and ELISA. ANCA was measured in both active and inactive stage of the disease. RESULTS: ANCA was present in 5 patients (5/10 : 50%) with active CSS phase and all ANCA patient results showed perinuclear pattern by IF assay and myeloperoxidase specific results by ELISA. Patients with ANCA were older (average age : 58.0) and had higher incidence of renal involvement (4/5 : 80%) than was found with ANCA negative patients (average age; 38.4, no patients with renal involvements). Among 5 patients with ANCA, one had rapidly progressive glomerulonephritis and one had alveolar hemorrhage. Remission was induced for 4 ANCA positive patients by corticosteroid and/or immunosuppressive drug and one required long term maintenance hemodialysis. ANCA titer changed in parallel with disease activity, such as proteinuria, hematuria and alveolar hemorrhage. No significant differences in regard to eosinophilia, serum IgE and CRP titer were found between ANCA positive and negative patients. CONCLUSION: These results strongly indicate that MPO-ANCA may play an important role in the pathogenesis of vascultis, such as renal injury and alveolar hemorrhage in CSS.

Adult↗
PubMed1998

[A case with rheumatoid arthritis complicated with ANCA-associated vasculitis].

A 50-year-old woman with rheumatoid arthritis (RA) developed constitutive symptoms such as fever and weight loss, mononeuritis multiplex and rapidly progressive glomerulonephritis (RPGN). The renal biopsy revealed crescentic glomerulonephritis (CrGN) with few immune deposits such as IgG and C 3 and necrotizing vasculitis, which led to the pathological diagnosis of microscopic polyangiitis (MPA). Moreover the high serum level of anti-myeloperoxidase (MPO) antibody, one of the anti-neutrophil cytoplasmic antibody (ANCA), suggested that she had ANCA-associated vasculitis. The renal prognosis of the ANCA-associated vasculitis is said to be poor unless patients were treated in the early phase of the disease. As we started to treat the patient when her serum creatinine level (sCr) was 1.7 mg/dl and creatinine clearance (CCr) was 27 ml/min, her renal function returned to the almost normal level (sCr = 0.6, CCr = 91). It is well known that patients with RA may develop various kinds of extraarticular manifestations which are usually related to immune-complex mediated vasculitis, what we call malignant RA. We emphasize that ANCA-associated vasculitis is another important complication of RA. When we see a RA patient with constitutional symptom, abnormal urinary sediments and other clinical signs of vasculitis such as mononeuritis multiplex, ANCA-associated vasculitis should be considered. Since the early diagnosis and treatment of ANCA-associated vasculitis is a key to prevent renal failure, it is encouraged to measure the serum ANCA titer for not only the diagnosis of such patients but the evaluation of their clinical course.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1997

Decrease in amplified telomeric sequences and induction of senescence markers by introduction of human chromosome 7 or its segments in SUSM-1.

Introduction of human chromosome 7 by microcell-mediated chromosome transfer suppresses indefinite division of SUSM-1, an in vitro established human fibroblast line. This cell line has unusually long telomeric sequences although it lacks detectable telomerase activity. Thus, we examined whether such telomeric sequences change upon introduction of chromosome 7 or its segments. In the microcell hybrids that stopped dividing by introduction of chromosome 7, the telomeric sequences were found to be lost or markedly diminished. Introduction of various fragments (2-40 Mb) of chromosome 7 contained in radiation hybrids gave similar results. On the other hand, the telomeric sequences were not altered significantly in the unsuppressed hybrids, a revertant of one suppressed clone, or subclones of SUSM-1 used as controls. In the suppressed microcell hybrids, the distribution of a mortality marker, mortalin, was changed to the cytosolic type of mortal cells from the immortal type of perinuclear fibres. Also, senescence-associated beta-galactosidase was induced to a level similar to that of normally senesced diploid fibroblasts. These results suggest that human chromosome 7 induces senescence in SUSM-1 by suppressing its telomere maintenance mechanism, which does not depend on telomerase.

Animals↗