Biomedical subjects

K Isobe

Publications and source records attributed to K Isobe.

At least 91 records · Page 5Linked to original sources

PubMed1999

Mitogen-activated protein kinase pathway mediates peroxynitrite-induced apoptosis in human dopaminergic neuroblastoma SH-SY5Y cells.

Peroxynitrite, a product of nitric oxide and superoxide, is one of the most potent oxidants and it has been suggested to be involved in many neurodegenerative disorders. The mechanism of the cytotoxicity by peroxynitrite was examined using 3-morpholinosydonimine (SIN-1) as a peroxynitrite donor and SH-SY5Y cells as a model of dopamine neurons. SIN-1 was found to induce apoptotic cell death with typical nucleosomal DNA fragmentation with activation of caspase 3-like proteases. The signal transduction of apoptosis was studied in concern to mitogen-activated protein kinases (MAPKs). After SIN-1 treatment, phosphorylation of p38 was detected, followed by that of Erk. SB202190, an inhibitor of p38, suppressed Erk phosphorylation to the basal level and partially reduced the activation of caspase 3-like proteases and also the cell death. These results suggest that peroxynitrite may activate p38 MAPK pathway to induce apoptosis in dopamine cells via activation of caspase 3-like proteases.

Antioxidants↗

PubMed1999

Accelerated development and aging of the immune system in p53-deficient mice.

Development and aging of the immune system lead to an accumulation of memory T cells over the long term. The predominance of T cells of the memory phenotype in the T cell population induces an age-related decline in protective immune responses. We found that development and aging of the immune system were accelerated in p53-deficient (p53-/-) mice; the accumulation of memory T cells was spontaneously accelerated, and a strong T cell-dependent Ab response and Th2 cytokine expression (IL-4, IL-6, and IL-10) were induced by Ag stimulation in young p53-/- mice in the developmental stage. The high T cell proliferative response in the young mice rapidly progressed to a depressed proliferative response in adult mice. It was suggested that the loss of regulation of the cell cycle, DNA repair, and apoptosis by p53 deficiency potentially leads to immunosenescence with the accumulation of memory T cells.

Aging↗

PubMed1999

Evidence for the interaction between Translin and GADD34 in mammalian cells.

To examine the function of GADD34, we used the yeast two-hybrid system to clone the protein that interacts with the murine GADD34 gene product. We utilized, as bait, the product of the GADD34 cDNA deletions including the PEST region and the gamma(1)34.5 domain. One of the cDNAs cloned encoded murine Translin which is known to bind to the DNA sequence detected in the DNA translocation. The interaction between GADD34 and Translin was also confirmed by an in vitro binding assay and in vivo two-hybrid analysis in NIH 3T3 cells. Although GADD34 expression was significantly elevated with methyl methanesulfonate treatment, we could not detect the induction of Translin mRNA.

3T3 Cells↗

PubMed1999

Leptin directly stimulates catecholamine secretion and synthesis in cultured porcine adrenal medullary chromaffin cells.

Leptin, a protein encoded by the ob gene, is an adipose tissue-derived signaling factor involved in body weight homeostasis. The hypothalamus is a major site of central action for leptin. However, mounting evidence indicates expression of leptin receptor mRNA in various peripheral organs including the adrenal medulla. Therefore, we investigated the effects of leptin on catecholamine secretion and synthesis in cultured porcine adrenal medullary chromaffin cells. We initially confirmed the expression of leptin receptor (Ob-Rb) mRNA in cultured porcine adrenal medullary cells. Murine recombinant leptin (>==50 nM) strongly induced the release of both epinephrine (E) and norepinephrine (NE) from chromaffin cells. Removal of external Ca(2+) significantly suppressed these effects. Also, leptin (>==1 nM) enhanced nicotine-induced increases in E- and NE. Leptin (1, 10, 100 nM) significantly increased tyrosine hydroxylase (TH) (a rate-limiting enzyme in the biosynthesis of catecholamine) mRNA levels in a concentration-dependent manner. Furthermore, leptin (1, 10, 100 nM) significantly induced increases in cAMP levels, suggesting that the stimulatory effects on TH mRNA are mediated, at least in part, by the cAMP/protein kinase A pathway. These results indicate that leptin directly stimulates catecholamine release and synthesis, which in turn may potentiate the anti-obesity effects of leptin.

Animals↗

PubMed1999

Accurate and sensitive high-performance liquid chromatographic method for geometrical and structural photoisomers of bilirubin IX alpha using the relative molar absorptivity values.

It has been reported that considerable differences exist between the relative molar absorptivity values of the geometrical and structural photoisomers of bilirubin. We have devised an accurate HPLC method for photoisomer quantification based on the following principle: the sum of both the integrated peak areas corrected by each factor for each photoisomer, and the integrated peak area of unchanged (ZZ)-bilirubin [(ZZ)-B] after an anaerobic photoirradiation, should be constant and equal to the integrated peak area of initial (ZZ)-bilirubin [(ZZ)-Bi] before photoirradiation. On this basis, the following equation can be used to determine each factor. [equation: see text] alpha, beta, gamma and delta represent the factors used to correct the integrated peak areas of individual bilirubin photoisomers, and they are arranged in the order of the formula. It was demonstrated that the relative 455 nm molar absorptivity values for (ZZ)-bilirubin and all its geometrical and structural photoisomers, i.e., (ZZ)-bilirubin, (ZE)-bilirubin (EZ)-bilirubin, (EZ)-cyclobilirubin (= lumirubin) and (EE)-cyclobilirubin in the HPLC eluent, are, respectively, 1.0, 0.81 (= alpha), 0.54 (= beta), 0.47 (= gamma) and 0.39 (= delta).

Bilirubin↗

PubMed1999

Both Sp1 and Sp3 are responsible for p21waf1 promoter activity induced by histone deacetylase inhibitor in NIH3T3 cells.

Histone deacetylase inhibitor-induced expression of p21WAF1 is p53 independent. In the present study, we provide evidence that trichostatin A (TSA), a specific inhibitor of histone deacetylase, can elevate H3 and H4 acetylation and p21WAF1 expression in NIH3T3 cells at first. To identify the transcription factor which is responsible for histone deacetylase inhibitor-induced expression of p21WAF1 and understand the potential events occurred during this process, we analyze the response of the mouse p21WAF1 promoter to TSA in detail. The region responsive to TSA treatment in the p21 promoter is located -100 bp upstream from transcription initiation site and contains a GC-box. The mutation introduced into this GC-box decreases most of the basal and TSA-induced promoter activity. The results from gel-shift assay show that Sp1 and Sp3 bind to this GC-rich region. Cotransfection with Sp1 and/or Sp3 expression constructs elevate both basal and induced promoter activity, and this elevation is dependent on the present of the GC-box. By contrast, cotransfection with reverse oriented Sp1 or Sp3 cDNA decreased basal and induced-promoter activity, as well as GC-box dependency. These findings provide physical and functional evidence which strongly indicated that both Sp1 and Sp3 are responsible for TSA-induced transactivation of the murine p21WAF1 promoter in NIH3T3 cells.

3T3 Cells↗

PubMed1999

Cooperative interaction of NF-kappaB and C/EBP binding sites is necessary for manganese superoxide dismutase gene transcription mediated by lipopolysaccharide and interferon-gamma.

Expression of the manganese superoxide dismutase (Mn-SOD) is induced by pro-inflammatory cytokines. We investigated the cis-acting elements within a tumor necrosis factor-responsive element (TNFRE) which was identified in the second intron of the murine Mn-SOD gene. Site-directed mutagenesis, reporter plasmid transfection studies and electrophoretic mobility shift assays demonstrated that inducible transcription factors enhanced the transcriptional activity of the Mn-SOD gene through the TNFRE. The cooperation between proteins binding to the newly identified NF-kappaB and C/EBP sites led to synergistic gene transcription. This report provides the first evidence that cooperation between two distinct cis-acting elements may be required for induction of Mn-SOD gene expression mediated by lipopolysaccharide and interferon-gamma.

3T3 Cells↗

PubMed1999

Transcomplementation between different types of respiration-deficient mitochondria with different pathogenic mutant mitochondrial DNAs.

Two cell lines were used for determination of whether interaction occurred between different types of respiration-deficient mitochondria. One was a respiration-deficient rho- cell line having mutant mitochondrial DNA (mtDNA) with a 5,196-base pair deletion including five tRNA genes (tRNAGly, Arg, Ser(AGY), Leu(CUN), His), DeltamtDNA5196, causing Kearns-Sayre syndrome. The other was a respiration-deficient syn- cell line having mutant mtDNA with an A to G substitution at 4,269 in the tRNAIle gene, mtDNA4269, causing fatal cardiomyopathy. The occurrence of mitochondrial interaction was examined by determining whether cybrids constructed by fusion of enucleated rho- cells with syn- cells became respiration competent by exchanging their tRNAs. No cybrids were isolated in selection medium, where only respiration-competent cells could survive, suggesting that no interaction occurred, or that it occurred so slowly that sufficient recovery of mitochondrial respiratory function was not attained by the time of selection. The latter possibility was confirmed by the observations that heteroplasmic cybrids with both mutant mtDNA4269 and DeltamtDNA5196 isolated without selection showed restored mitochondrial respiration activity. This demonstration of transcomplementation between different respiration-deficient mitochondria will help in understanding the relationship between somatic mutant mtDNAs and the roles of such mutations in aging processes.

Cardiomyopathies↗

PubMed1999

A mitochondrial DNA mutation cosegregates with the pathophysiological U wave.

In a family with long QT syndrome (LQT2), some individuals who did not harbor the HERG mutation had a prolonged QTU interval on electrocardiograms after exercise. It may be determined or modified by other gene(s) or factor(s). The sequence analysis of mtDNA in these individuals of this family showed a candidate pathogenic mutation at 3394 in the ND1 gene. The cybrids (mutation at 3394) showed significantly reduced NADH-CoQ reductase (complex I) activity and O2 consumption to normal levels. These inhibitory effects on respiratory function may result in the depletion of ATP and could possibly produce an increase in Ca2+ concentration in cytosol, and it may lead to the prolongation of the QTU intervals on electrocardiograms. Therefore, we stated that the 3394 mutation in the ND1 gene is pathogenic and could be the cause of prolongation of the QTU intervals or modification of the phenotypes of not only congenital but also so-called "acquired drug-induced long QT syndrome."

Adolescent↗

PubMed1999

Cloning of a GADD34-like gene that interacts with the zinc-finger transcription factor which binds to the p21(WAF) promoter.

A histone deacetylase inhibitor has been shown to induce differentiation of many cancer cells and senescence-like state of human fibroblasts. Previously, our data suggested that the region responsive to trichostatin A (TSA), a specific inhibitor of histone deacetylase, treatment in the p21(WAF1) promoter is located -100 bp upstream from transcription initiation site and contains a GC-box where both Sp1 and Sp3 are responsible. Here we show that another zinc-finger transcription factor, BFCOL1, which binds to the proximal proalpha2(I) collagen promoter, could also bind to this GC-box of the p21 promoter. In addition, we cloned a gene whose product interacts with this factor by yeast two-hybrid method. The cloned gene was a variant of GADD34 and lacking one PEST region. We found that this cDNA product decreased the DNA binding activity of BFCOL1 to the GC-rich region of p21 minimal promoter.

Animals↗

PubMed1999

Linkage between melanocytic tumor development and early burst of Ret protein expression for tolerance induction in metallothionein-I/ret transgenic mouse lines.

We examined the basis of the all or none difference in inducing melanocytic tumor development among three transgenic mouse lines (304, 192 and 242) to which the same promoter-enhancer (metallothionein-I) and oncogene (ret) were introduced. We initially demonstrated that both skin melanosis and Ret protein expression in skin, thymus and brain first became detectable before or immediately after birth in the mice of the tumor developing lines (304 and 192), whereas they became detectable a few days after birth in the mice of the non-tumor developing line (242) by Western blotting and immunohistochemical analysis. Interestingly, the Ret protein expression in skin developed rapidly after birth as a burst with peak levels on 0.5-1.5 day newborns of lines 304 and 192 and on 7.0-7.5 day-old mice of line 242. The levels of autophosphorylation of Ret kinase in skin were, however, invariable among these three transgenic mouse lines. The mice of line 242, but not those of lines 192 and 304, responded to Ret protein immunization by increased antigen-dependent lymphocyte proliferation and T-cell-mediated tumor growth suppression in vitro. Furthermore, ret-transgenic mice of line 242, but not line 304, rejected the subcutaneously transplanted tumors that had originally developed in a mouse of line 304. These results suggest that whether oncogene product-specific-tolerance is established or not to antitumor immunity may be decided by the dynamics of ret oncogene expression before and after delivery and this is the primary factor determining development or non-development of melanoma.

Animals↗

PubMed1999

Acute arterial occlusion associated with total knee arthroplasty.

Acute arterial occlusion is a rare but limb-threatening complication in total knee arthroplasty. Most of the previously reported cases of this complication required surgical intervention. This report illustrates an unusual case of this complication that was managed conservatively with an acceptable outcome. The case is also indicative of the etiology and the optimal prevention of this complication. In a patient with advanced arteriosclerosis, as indicated by vascular calcification around the knee or in the abdomen, knee arthroplasty should be performed without a tourniquet, and intra-operative manipulation should be done cautiously because of the potential for intimal disruption.

Acute Disease↗

PubMed1999

Effects of PAMP on mRNAs coding for catecholamine-synthesizing enzymes in PC12 cells.

Proadrenomedullin N-terminal 20 peptide (PAMP) is a novel hypotensive peptide found in the N-terminal portion of the precursor of adrenomedullin (AM). Although PAMP and AM originate from the same precursor and exert both a potent hypotensive action, they seem to control blood pressure through different mechanisms. To gain new insight into the anticholinergic actions of PAMP, we determined the effects of PAMP on the tyrosine hydroxylase (TH)- and dopamine beta-hydroxylase (DBH) mRNA expression in the rat pheochromocytoma cell line PC12 stimulated by nicotine. PAMP (> or =1 microM) significantly inhibited the nicotine-induced increases of TH- and DBH mRNA expression in a concentration-dependent manner. Also, PAMP at the concentrations (> or =1 microM) significantly inhibited nicotine-induced cyclic adenosine monophosphate (cAMP) production. These results indicate that the anticholinergic hypotensive actions of PAMP can be explained, at least in part, by its inhibition of the expression of mRNAs coding for catecholamine-synthesizing enzymes, and that the inhibitory effect is mediated by the cAMP/protein kinase A pathway.

Adrenomedullin↗

PubMed1999

Diffuse large B cell lymphoma expressing the natural killer cell marker CD56.

The expression of the natural killer (NK) cell antigen, CD56, in hematological malignancies is rare. However, there are several reports that some hematological malignancies, such as T/NK cell lymphoma, multiple myeloma (MM) and acute myeloid leukemia (AML), express this molecule. In B cell non-Hodgkin's lymphomas (NHL), however, very limited number of cases have been reported to express CD56 molecule. Although one study has recently described that half of microvillous B cell lymphoma (MVL), an uncommon subset of large cell lymphoma, expressed CD56, there have been no reports about most common type of B-NHL, diffuse large B cell lymphoma (DLBL) other than a mention of weak CD56 expression in one of 83 DLBL. We herein presented the first case of diffuse large B cell lymphoma expressing CD56 clearly. The immunophenotype determined by immunostaining and flow cytometric analysis was CD10+, CD19+, CD20+, CD45RO-, CD3- and CD56+. On immunohistochemical study, neither bcl-2 nor TIA-1 was positive for tumor cell. Monoclonal immunoglobulin heavy chain (IgH) gene rearrangement was detected, and the sequence analysis of the variable region of IgH (VH) suggested that this tumor was derived from antigen selected post germinal center B cell. Conventional combination chemotherapy (CHOP) was administered, and the patient has still been in complete remission for 10 months.

Adolescent↗

PubMed1999

Successive occupancy by immediate early transcriptional factors of the tyrosine hydroxylase gene TRE and CRE sites in PACAP-stimulated PC12 pheochromocytoma cells.

We previously demonstrated that pituitary adenylate cyclase-activating polypeptide (PACAP) coordinately upregulates the expression of the tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) genes by activating the cyclic AMP (cAMP) and protein kinase C (PKC) signaling pathways. In this study, we examined the effects of PACAP on the expression of fos and jun immediate early gene (IEG) families, expression of which can be up-regulated by both PKC and cAMP signaling pathways, in rat pheochromocytoma cell line PC12 cells. PACAP potently stimulated the expression of c-fos, fosB junB and junD, but not c-jun mRNAs, at doses of 0.1-10 nM, as revealed by Northern blot analysis. The effects of PACAP on the expression of these mRNAs in PC12 cells was rapid (30-60 min) and dose-dependent. PACAP administration induced maximum expression of c-fos, fosB and junB mRNA after 60 min, and of junD mRNA after 8 h. Gel mobility shift assays using synthetic DNA oligonucleotides corresponding to the TH 5'-flanking region and nuclear extracts from PC12 cells demonstrated that PACAP enhanced formation of the specific protein complexes which bind to the TPA-responsive element (TRE) and cAMP-responsive element (CRE), respectively. Gel shift and supershift analyses showed that the TRE-binding factors and CRE-binding factors comprised fosB, c-fos, junB, and junD, and CRE-binding protein (CREB) and junD, respectively. JunB was dominant in the TRE-binding complexes at 4 h after addition of PACAP, whereas both JunD and JunB were dominant at 12 h. These results suggest that agonist occupancy of PACAP receptors activates transcriptional factors (Fos/Jun families and CREB) that interact with the TRE and CRE sites of the TH 5'-flanking region, contributing to transcriptional activation of TH gene.

Animals↗

PubMed1999

Mechanically elicited nerve root discharge: mechanical irritation and waveform.

OBJECTIVE: Intraoperative monitoring is very important for protecting nerve roots during lumbar surgery for spinal degeneration. Our objective was to evaluate the correlation between the type of mechanical irritation and waveform by mechanically elicited EMGs during the surgery. METHOD: Mechanically elicited EMGs were recorded bilaterally on muscle groups innervated by the lumbar nerve roots in the area of surgery in 24 consecutive patients with lumbar spinal degenerative disease. RESULTS: It was confirmed that surgical irritation produced 3 types of waveforms as discharges from nerve roots; short, waning and continuous discharges. Each waveform was easily elicited mechanically and was sensitively related to the type and strength of mechanical stimulation. CONCLUSION: It was indicated that the mechanical irritation on the root could elicit the nerve root discharge with no post-operative nerve root deficit. It may be useful to monitor the mechanically elicited EMGs during the surgery for spinal degeneration.

Adult↗

PubMed1999

Adenovirus strains of subgenus D associated with nosocomial infection as new etiological agents of epidemic keratoconjunctivitis in Japan.

Adenovirus strains of a new type were isolated from patients with epidemic keratoconjunctivitis. They were not completely neutralized by any antiserum against adenovirus prototypes. PCR followed by restriction endonuclease analysis demonstrated that they were type 8. PCR followed by sequencing revealed a high homology rate between them and type 9.

Adenoviridae↗

PubMed1999

Clinicopathological evaluation of the Revised European-American Classification of Lymphoid Neoplasms (REAL) in Japan.

After the publication of a Revised European-American Classification of Lymphoid Neoplasms (REAL classification) in 1994, there have been reports from Europe and America regarding its practical utility and clinical significance. However, no studies have been published from Eastern countries including Japan. It has been well recognized that the distribution of malignant lymphoma in Japan is quite different from that seen in Western countries. In addition, some new entities have also been described in the REAL classification. Therefore, it seems important to examine its practical utility and clinical significance in Japan. Of the 579 cases reviewed, approximately 68% were B-cell non-Hodgkin's lymphoma (NHL) followed by 27% T-cell lymphomas. Hodgkin's disease (HD) comprised only 5% of all cases, making the ratio of NHL to HD 20.6. The most common type was diffuse large B-cell lymphoma which represented about 37% of all cases. Peripheral T-cell lymphomas, unspecified (PTCL), occurred in 15% whereas marginal zone B-cell lymphoma followed (14.9%). However, follicle center lymphoma (FCL) was less common (4.4%) as has been previously reported. We evaluated the clinical significance of the new REAL classification in 244 cases. International Prognostic Index (IPI) was a powerful predictor of survival (p<0.0001), and the immunophenotype was significant (p<0.05). Furthermore, here, we also attempt to establish a prognostic scheme based on the histologic type. In conclusion, the REAL classification appears to be useful and clinically significant in Japan.

Adolescent↗