Biomedical subjects

N Ogata

Publications and source records attributed to N Ogata.

At least 73 records · Page 4Linked to original sources

PubMed1999

[A case of prostate cancer associated with osteolytic bone metastases].

It is well known that prostate cancer metastasizes bone with osteoblastic change and that osteolytic change is rare. We report a case of prostate cancer that had bone metastases which were all osteolytic. A 62-year-old man was referred to our department because of abnormal prostatic acid phosphatase and pain in his right upper arm. Digital examination revealed an enlarged and hard prostate. A computed tomographic scan revealed multiple osteolytic changes and a bone scintigraphy was positive at these sites. Histopathology of both prostate and humerus showed poorly differentiated adenocarcinoma. He received castration and antiandrogen as hormonal therapy, but the patient's prostate specific antigen did not normalize. Therefore this case was suspected to be hormone-refractory prostate cancer.

Adenocarcinoma↗

PubMed1999

Novel patterns of amino acid mutations in the hepatitis B virus polymerase in association with resistance to lamivudine therapy in japanese patients with chronic hepatitis B.

Lamivudine is effective in suppressing replication of hepatitis B virus (HBV). However, the emergence of HBV variants resistant to lamivudine is a concern. Lamivudine resistance has been attributed mainly to a substitution of isoleucine or valine for methionine at residue 550 (M550I or M550V) in the catalytic site of the virus polymerase. A substitution of methionine for leucine at residue 526 (L526M) has also been identified. To examine such virus genotypic mutations in Japanese patients, we studied five patients with chronic hepatitis B, who showed HBV breakthrough while on a 1-year lamivudine treatment. The entire nucleotide and deduced amino acid sequences of the proposed reverse transcriptase domain of the polymerase gene were determined on HBV DNA amplified by polymerase chain reaction from patient sera collected at the start and at the end of therapy. The HBV sequences from all five patients were of genotype C. In four patients, a substitution of valine or isoleucine for leucine at residue 426, which has not been reported previously, emerged in combination with M550I. One also harbored L526M. In the remaining patient, an alteration of leucine to methionine at residue 428 co-occurred with M550V. Longitudinal study of the mutations showed that the two or three mutations in each patient emerged almost simultaneously 4 weeks before or at the time of breakthrough and were replaced by wild-type virus after completing the therapy. Our results indicate that occurrence of HBV polymerase mutations at residue 426 in combination with M550I is frequent in Japanese or genotype C virus-in- fected patients who develop resistance to lamivudine.

Adult↗

PubMed1998

The antibody specific for myristoylated alanine-rich C kinase substrate phosphorylated by protein kinase C: activation of protein kinase C in smooth muscle cells in human coronary arteries.

Myristoylated alanine-rich C kinase substrate (MARCKS), a major substrate for protein kinase C, is distributed in a variety of cells. It has been reported that phosphorylation of MARCKS at serines 152 and 156 according to the numbering of rat brain MARCKS can be used as an indicator for protein kinase C activation in intact cells. To detect the activation of protein kinase C in vivo, we produced a specific antibody against MARCKS phosphorylated at serines 152 and 156. We synthesized a phosphopeptide which contained phosphoserines 152 and 156 and prepared the antibody specific for this phosphopeptide. Immunoblot analysis with both purified MARCKS and the cytosol fraction from rat brain revealed that the antibody reacted only with MARCKS phosphorylated by protein kinase C. The antibody was suitable for immunoblot analysis and immunostaining with cultured human coronary artery smooth muscle cells. Phosphorylation of MARCKS was increased about eightfold by the treatment of the cells with phorbol 12-myristate 13-acetate, a protein kinase C activator. Furthermore, treatment of the cells with endothelin-1 and tumor necrosis factor alpha increased phosphorylation of MARCKS. Interestingly, phosphorylation of MARCKS was clearly observed in smooth muscle cells in atherosclerotic lesion of subjects at autopsy. These results suggest that the antibody is useful for examination of the activation of protein kinase C in vascular smooth muscle cells in vivo.

Animals↗

PubMed1998

Creation of genetic information by DNA polymerase of the archaeon Thermococcus litoralis: influences of temperature and ionic strength.

DNA polymerase of the archaeon Thermococcus litoralis can synthesize a long stretch of linear double-stranded DNA in the complete absence of added primer and template DNAs. This finding suggests that genetic information can potentially be created by protein. We report here the effects of temperature, ionic strength and pH on this ab initio DNA synthesis by the protein in vitro . When the temperature of the reaction was changed, the sequence of the product DNA changed markedly. For instance, the reaction products were (TAAT) n at 69 degrees C, (TATCCGGA) n at 84 degrees C and (TATCGCGATAGCGATCGC) n at 89 degrees C. The ionic strength of the reaction condition also affected the sequence: it was (TATCTAGA) n with 0 mM KCl, (TATATACG) n with 50 mM KCl and (TATAGTTATAAC) n with 100 mM KCl at 74 degrees C. When the pH of the reaction condition was changed from 6.8 to 10.8, the size of the product DNA decreased, but its sequence did not. These results demonstrate that DNA synthesized ab initio by DNA polymerase of T.litoralis is markedly influenced by the reaction conditions. The results also suggest that genetic information that might have been created by protein on the early earth is strongly influenced by environmental factors.

Base Sequence↗

PubMed1998

Creation of genetic information by DNA polymerase of the thermophilic bacterium Thermus thermophilus.

Genetic information encoded in a template of a genome is replicated in a complementary way by DNA polymerase or RNA polymerase with high fidelity; no creation of information occurs in this reaction unless an error occurs. We report here that DNA polymerase of the thermophilic bacterium Thermus thermophilus can synthesize up to 200 kb linear double-stranded DNA in vitro in the complete absence of added primer and template DNAs, indicating that genetic information is actively created by protein. This ab initio DNA synthesis occurs at 74 degrees C and requires magnesium ion. There is a lag time of approximately 1 h and then the reaction proceeds linearly. The synthesized DNAs have a variety of sequences; they are mostly tandem repetitive sequences, e.g. (CATGTATA) n , (TGTATGTATACATACATA) n and (TATACGTA) n . Some degenerate sequences of these basic repeat units are also found. The similar repetitive sequences are found in many natural genes. These results, together with similar results found using DNA polymerase of archaeon Thermococcus litoralis , suggest that creative, non-replicative synthesis of DNA by protein was a driving force for diversification of genetic information at a certain stage of the evolution of life on the early earth.

Cloning, Molecular↗

PubMed1998

Genomic DNA sequence of a rice gene coding for a pullulanase-type of starch debranching enzyme.

A genomic DNA containing a rice (Oryza sativa L., cv. Norin-8) gene coding for a pullulanase-type starch debranching enzyme (EC 3.2.1. 41) was sequenced (EMBL/GenBank/DDBJ accession number AB012915). Along the 15, 248 bp DNA, the pullulanase gene is split into 26 exons. The four pullulanase consensus regions are positioned in the middle portion of the sequence and are separated by long introns and 1-3 exons. Comparison of the rice cv. Norin-8 pullulanase genomic structure with that of barley pullulanase (limit dextrinase) (F. Lok et al., EMBL/GenBank/DDBJ accession number AF022725) indicates that most of the pullulanase exons are highly conserved. Alignment of the nucleotide bases of rice exon 8 with those of barley exon 8-intron 8-exon 9 fragment suggests that the 85 bp internal sequence of rice exon 8 was originally an intron, a possibility further indicated by the absence in barley and spinach (A. Renz et al., EMBL/GenBank/DDBJ accession number X83969) pullulanases of amino acid residues encoded by the 85 bp fragment.

Base Sequence↗

PubMed1998

JAK2 and JAK1 constitutively associate with an interleukin-5 (IL-5) receptor alpha and betac subunit, respectively, and are activated upon IL-5 stimulation.

The human interleukin-5 receptor (hIL-5R) consists of a unique alpha subunit (hIL-5Ralpha) and a common beta subunit (betac) that activate two Janus kinases (JAK1 and JAK2) and a signal transducer and activator of transcription (STAT5). The precise stoichiometry of the hIL-5R subunits and the role of JAK kinases used in IL-5 signaling were investigated. We analyzed the interaction between hIL-5Ralpha and betac by immunoprecipitation using anti-hIL-5Ralpha and anti-betac monoclonal antibodies. The binding of JAK1 and JAK2 to each hIL-5R subunit was also evaluated in the hIL-5-responsive cell line, TF-h5Ralpha. It was observed that IL-5 stimulation induced the recruitment of betac to hIL-5Ralpha, although in the absence of IL-5 the subunits remain independent. In the absence of IL-5, JAK2 and JAK1 were associated with hIL-5Ralpha and betac, respectively. IL-5 stimulation resulted in tyrosine phosphorylation of JAK2, JAK1, betac, and STAT5. Moreover, IL-5-induced dimerization of IL-5R subunits caused JAK2 activation and betac phosphorylation even in the absence of JAK1 activation. Furthermore, tyrosine phosphorylation of JAK1 was dependent on the activation of JAK2. Detailed study of the C-terminal truncated cytoplasmic domain of hIL-5Ralpha revealed that the cytoplasmic stretch at position 346-387, containing the proline-rich region, is necessary for JAK2 binding. These observations suggest that activation of hIL-5Ralpha-associated JAK2 is indispensable for the IL-5 signaling event.

Humans↗

PubMed1998

Acute glucosuria after continuous glucocorticoid loading in the rat in vivo.

We investigated the effects of the continuous infusion of various steroids in rats on renal tubular reabsorption of glucose in vivo to elucidate the pathogenesis of steroid-induced glucosuria. Urinary glucose excretion increased 60 min after administration of dexamethasone (2.38 mM). By 120 min, urinary excretion of glucose was three times higher in the dexamethasone group than in the control group (24.1 +/- 4.6 versus 72.4 +/- 16.7 micromol); the plasma level of glucose did not increase. Dexamethasone had no effect on the resorption of 1,5-anhydro-D-glucitol, which is a glucose-resembling polyol that is actively absorbed by the renal tubules as glucose. Neither estradiol nor progesterone increased urinary excretion of glucose. These findings suggest that continuous administration of a high-dose glucocorticoid selectively influences the glucose reabsorption system in the kidney.

Animals↗

PubMed1998

Spreading and migration of human glioma and rat C6 cells on central nervous system myelin in vitro is correlated with tumor malignancy and involves a metalloproteolytic activity.

Malignant gliomas infiltrate the brain preferentially along myelinated fiber tracts. Central nervous system (CNS) myelin, however, contains inhibitory proteins that block axon regeneration, neurite outgrowth, and cell spreading of astrocytes and fibroblasts. We tested 5 human brain tumor cell lines, 1 rat brain tumor cell line, and 29 short-term cultured specimens from human brain tumors for their ability to spread and migrate on a CNS myelin substrate. Low-grade and pilocytic astrocytoma, ependymoma, medulloblastoma, and meningioma cell lines as well as primary cultures were strongly sensitive to the inhibitory proteins present in the CNS myelin. In contrast, glioblastomas, anaplastic astrocytomas, and oligodendrogliomas were able to spread and migrate on CNS myelin-coated culture dishes, demonstrating that within the gliomas, the ability to overcome the inhibitory effects of the CNS myelin is correlated with the grade of malignancy of the original tumor. Cell spreading of glioblastomas and anaplastic astrocytomas specifically on a CNS myelin substrate was strongly inhibited by the metalloprotease blocker O-phenanthroline and the peptide derivative carbobenzoxy-Phe-Ala-Phe-Tyr-amide, whereas blockers for serine, aspartyl, and cysteine proteases had no effect. Enzymatic peptide degradation assays revealed the presence of a phosphoramidon-sensitive and thiorphan-insensitive metalloproteolytic activity in the plasma membranes of high-grade glioma cells. These results suggest a crucial involvement of a membrane-bound metalloendoprotease in the process of invasive migration of malignant gliomas along CNS white matter fiber tracts.

Animals↗

PubMed1998

Immunolocalization of transforming growth factor beta during wound repair in rat retina after laser photocoagulation.

BACKGROUND: Scatter photocoagulation induces regression of retinal neovascularization, but the mechanism of its therapeutic effect is incompletely understood. To elucidate the mechanism of therapeutic effect of photocoagulation is the main focus of our research. We have already demonstrated basic fibroblast growth factor (bFGF) immunolocalization during retinal wound repair following laser photocoagulation. Transforming growth factor beta (TGF beta) reportedly inhibits endothelial cell growth and bFGF-induced cell proliferation in vitro. In the present study, we evaluated the immunohistochemical localization of TGF-beta 1 and -beta 2 during wound repair in the rat retina following laser photocoagulation. METHODS: Krypton laser photocoagulation was performed on the eyes of pigmented rats. The eyes were then enucleated on day 1, 3, 7, 14, 28 or 56 following the photocoagulation and enrolled into the analysis of immunohistochemical localization of TGF-beta 1 and -beta 2. RESULTS: Immunoreactivity for TGF-beta 1 and -beta 2 was present in the ganglion cell layer and photoreceptor outer segments of the normal adult rat retina. The cytoplasm of RPE cells at the photocoagulated lesion showed intense TGF-beta 1 and -beta 2 immunoreactivity on day 3 after laser photocoagulation. Macrophages that migrated into the lesion lacked positive staining for TGF-beta 1 and -beta 2. TGF-beta immunoreactivity in RPE cells continued to be upregulated for more than 1 month compared with that in normal RPE cells. Controls did not exhibit any positive staining. CONCLUSION: An elevated expression of TGF-beta immunoreactivity for a longer period of time than bFGF was observed in RPE cells at the photocoagulated lesion in vivo. In the late phase of retinal wound repair, TGF-beta may inhibit cell proliferation induced by mitogens, introduce an end stage of cellular events, and induce extracellular matrix induction.

Animals↗

PubMed1998

Apoptosis of photoreceptor cells in ornithine-induced retinopathy.

BACKGROUND: The intravitreal injection of ornithine produces selective damage to the retinal pigment epithelium (RPE) and results in a loss of RPE, choriocapillaris and photoreceptor cells. To elucidate the mechanism of secondary retinal atrophy, we investigated the presence of apoptotic cells in a rat model of ornithine-induced retinopathy. METHODS: At 6 and 12 h and 1, 2, 4, 7, 14 and 28 days after an intravitreal injection of L-ornithine hydrochloride in rat eyes, we removed the eyes and subjected them to histopathological examination. We detected apoptotic cells by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate digoxigenin nick end labeling (TUNEL) assay, which stains the 3'-OH ends of fragmented DNA. We used electron microscopy to detect the apoptotic cells morphologically. RESULTS: RPE cells were selectively damaged immediately after ornithine administration. TUNEL-positive photoreceptor cells appeared exclusively in the photoreceptor cell layer 12 h after ornithine administration. The number of TUNEL-positive cells increased throughout the 2 days following the injection, then decreased markedly. TUNEL-positive cells remained until 28 days, when the photoreceptor cells had disappeared. The ganglion cell layer, inner nuclear layer and damaged RPE cells were negative for TUNEL staining during all stages. The electron microscopic study also revealed the pyknotic nuclei of apoptotic photoreceptor cells. CONCLUSION: An intravitreal injection of ornithine caused primary damage to the RPE, and subsequently some of the photoreceptor cells revealed apoptosis by TUNEL assay. These findings suggest the dysfunction of the RPE causes photoreceptor cell death according to the intrinsic program of an apoptotic mechanism.

Animals↗

PubMed1998

Expression of basic fibroblast growth factor and its receptor mRNA in retinal tissue following ischemic injury in the rat.

BACKGROUND: Our purpose was to determine the time-dependent changes of expression of basic fibroblast growth factor (bFGF) and its receptor in pressure-induced retinal ischemia in rats. METHODS: Retinal ischemia was induced in Wistar rats by increasing the intraocular pressure to 110 mmHg for 45 min by cannulation into the eyes. At the end of the ischemic period, reperfusion of the retinal vasculature was confirmed. Localization of bFGF and FGF receptor-1 (FGF-R) mRNAs were evaluated by in situ hybridization at various times after reperfusion. The reverse-transcription polymerase chain reaction (RT-PCR) method was used to detect the expression of bFGF and FGF-R mRNA in the sensory retina. RESULTS: In normal sensory retina, bFGF and FGF-R mRNAs were observed in the ganglion cell layer and inner nuclear layer. bFGF gene expression in the sensory retina increased within 24 h, particularly at 6-12 h. FGF-R gene expression increased earlier than that of bFGF. By RT-PCR, expression of bFGF gene reached a peak at 6-24 h, and FGF-R reached a peak at 3-12 h. These RT-PCR results are comparable to those of in situ hybridization. CONCLUSIONS: These results demonstrate that transient retinal ischemia leads to the induction of bFGF mRNA synthesis, and suggest that bFGF has a protective role, e.g., a defense mechanism for the sensory retina.

Animals↗

PubMed1998

Supersensitivity of atherosclerotic artery to constrictor effect of cigarette smoke extract.

OBJECTIVE: The aim of this study was to assess whether contractile response of arteries to aqueous component of cigarette smoke extract (CSE) may be modulated in atherosclerotic arteries. METHODS: Thoracic aortas were isolated from control rabbits and from 1.5% cholesterol-fed rabbits, all of which had visible advanced atheromatous surface changes on the aortas. CSE was prepared by bubbling main stream of smoke from one cigarette with filter into 2 ml of phosphate-buffered saline. The thoracic aortic rings were suspended in organ chambers and tested with CSE (0.01-3.0 microliters/ml buffer in the organ chamber) after precontraction with 0.1 mumol/l of phenylephrine (PE). RESULTS: The contractile response to CSE was significantly greater in atherosclerotic aortas than in control aortas (the maximal contraction expressed as % of the precontraction; control aortas 10.8 +/- 2.8%, atherosclerotic aortas 42.6 +/- 4.7%; P < 0.01). The magnitude of the precontractions by PE was not different between control and atherosclerotic aortas. Exogenous addition of superoxide dismutase (SOD) significantly attenuated the CSE-induced contraction in both control and atherosclerotic aortas and pretreatment of aortic rings with diethyldithiocarbamate to deplete of endogenous vascular CuZn-SOD activity potentiated the CSE-induced contraction in control aortas, while it had no significant effect in atherosclerotic aortas. The vascular SOD activity was significantly lower in atherosclerotic aortas than in control aortas ((U/mg protein): control aortas 38.2 +/- 3.3, atherosclerotic aortas 18.5 +/- 2.4; P < 0.01). CONCLUSION: These results indicate that atherosclerotic arteries may be supersensitive to the constrictor effect of superoxide anion derived from CSE. The decrease in endogenous vascular SOD activity may partly contribute to the increased susceptibility to oxidative stress in atherosclerotic arteries.

Animals↗

PubMed1998

Differential expression of transforming growth factor-beta and its receptors in hepatocytes and nonparenchymal cells of rat liver after CCl4 administration.

BACKGROUND/AIMS: Transforming growth factor-beta (TGF-beta) is a family of multifunctional proteins that regulate hepatocyte proliferation, and biosynthesis of the extracellular matrix. In this study we examined whether modulation of TGF-beta receptor expression contributes to the liver diseases. METHODS: The mRNA expression of TGF-beta1, TGF-beta type I receptor (TGFbetaRI), TGF-beta type II receptor (TGFbetaRII) and TGF-beta type III receptor (TGFbetaRIII) in rat livers injured by CCl4 administration was studied by Northern blotting. The mRNA expression patterns were confirmed by in situ hybridization. RESULT: The peak of TGF-beta1 mRNA expression was observed 48 h after acute intoxication with CCl4 in nonparenchymal cells. However, the levels of TGFbetaRI and TGFbetaRII mRNA expression decreased from 24 h to 48 h and from 12 h to 48 h, respectively, and returned to the normal level by 72 h. TGFbetaRII mRNA expression was depressed more and for longer than that of TGFbetaRI mRNA. Analysis in separated hepatocytes and nonparenchymal cells from the injured livers indicated that the mRNA changes occurred in hepatocytes. Nonparenchymal cells expressed TGFbetaRI and TGFbetaRII mRNAs at constant levels during liver regeneration. TGFbetaRIII mRNA, which also decreased after 12 h, was not apparent in hepatocytes but only in nonparenchymal cells. CONCLUSIONS: These observations suggest that: (i) whenever TGF-beta1 is increased in CCl4-treated livers, it may induce liver fibrogenesis via nonparenchymal cells; (ii) the mitoinhibitory effect of TGF-beta1 on hepatocytes is transiently relieved by down-regulation of TGF-beta receptors for 72 h post-damage; and (iii) the resistance to TGF-beta growth inhibition between 24 to 48 h may be predominantly due to down-regulation of the expression of TGFbetaRII.

Animals↗

PubMed1998

Midkine expression in transient retinal ischemia in the rat.

PURPOSE: Midkine (MK), a 13-kDa heparin-binding growth factor, is known to exert neurotrophic activities on various nerve cells including retinal cells. To initiate studies toward determining the physiological role of endogenous MK, we investigated the spatial and temporal expression profile of MK before and after intraocular pressure-induced retinal ischemia. METHODS: Retinal ischemia was induced in Wistar strain rats by increasing the intraocular pressure to 110 mm Hg for 45 min via cannulation into the anterior chamber. The localization and abundance of the MK protein and mRNA were determined by the use of immunohistochemistry and in situ hybridization in the normal retina, as well as the retina after reperfusion. The protein expression profile was confirmed by Western blot analysis. RESULTS: Immunohistochemical analysis showed that MK protein was expressed in the ganglion cell layer, the inner portion of the inner nuclear layer, and in the retinal pigment epithelium of the normal rat. MK expression transiently decreased 3 h to 2 days after reperfusion, and then dramatically increased to a level higher than normal after 7 to 28 days. The temporal expression profile of the MK protein was confirmed by Western blot analysis. In situ hybridization analysis gave results comparable to those obtained with immunohistochemistry. CONCLUSIONS: MK was expressed in the neural cells of the retina in the normal state, but became more abundant after pressure-induced retinal ischemia. Thus, endogenous MK responds to ischemic treatment by an initial decrease in expression and then a period of expression above basal levels.

Animals↗

PubMed1998

Expression of vascular endothelial growth factor and its receptor, KDR, following retinal ischemia-reperfusion injury in the rat.

PURPOSE: There is considerable evidence that vascular endothelial growth factor (VEGF) mediates ocular neovascularization in retinal vascular diseases. We investigated the time-dependent changes in the expression of VEGF and its receptor KDR/ Flk in a transient retinal ischemia-reperfusion injury model. METHODS: Transient retinal ischemia was induced by increasing the intraocular pressure in albino rats eyes for 45 min. In situ hybridization was used to identify the retinal cells synthesizing VEGF mRNA and KDR mRNA at various times following reperfusion. Immunohistochemical analysis was also carried out to detect VEGF immunoreactivity. RESULTS: In the control, non-ischemic retinas, signals for VEGF mRNA and KDR mRNA were observed in the cells of the ganglion cell layer. Immunoreactivity to VEGF was also found in the nerve fiber layer, the ganglion cell layer, and the retinal pigment epithelial (RPE) cell layer. Immediately and 6 h after reperfusion, VEGF and KDR mRNA expression was markedly decreased, but recovered by 24 h to the levels observed in normal retinas. Immunoreactivity for VEGF was also decreased immediately and 6 h after reperfusion, and was detected in the endothelial cells of the retinal vessels after 24 h. Immunoreactivity to VEGF recovered by 48 h after reperfusion. CONCLUSIONS: The hybridization pattern of VEGF and KDR mRNA in the ganglion cell layer strongly suggests that the ganglion cells are the major source of this growth factor. The decrease of VEGF mRNA, KDR/Flk mRNA and VEGF protein levels after ischemia and recovery after reperfusion suggest that transient hypoxia might mediate short-term down-regulation of VEGF and KDR mRNA.

Animals↗

PubMed1998

Biphasic regulation of transcription factor nuclear factor-kappaB activity in human endothelial cells by lysophosphatidylcholine through protein kinase C-mediated pathway.

Lysophosphatidylcholine (lysoPC), which is generated in oxidized LDL (Ox-LDL) and abundantly exists in atherosclerotic arterial walls, has been shown to alter various endothelial functions and induces several endothelial genes expressed in atherosclerotic arterial walls. Nuclear factor-kappa B (NF-kappaB), a pleiotropic transcription factor, plays an important role in regulation of expression of various genes implicated in atherosclerosis. We have previously reported that lysoPC transferred from Ox-LDL to endothelial surface membrane activates endothelial protein kinase C (PKC), leading to modulated endothelial functions. This study was aimed at determining whether lysoPC could modulate activity of transcription factors in cultured human umbilical vein endothelial cells (HUVECs) by using electrophoretic mobility shift assay. LysoPC was found to increase DNA-binding activity of NF-kappaB in HUVECs within 15 minutes, which peaked at 1 to 2 hours and subsequently declined to the baseline level at 6 hours. Lower concentrations (5 to 15 micromol/L) of lysoPC markedly increased NF-kappaB activity, but higher concentration (50 micromol/L) of lysoPC inhibited the activity. Phorbol 12-myristate 13-acetate, a potent activator of PKC, also augmented NF-kappaB activity in HUVECs, mimicking the effects of lysoPC; furthermore, calphostin C and chelerythrine chloride, specific PKC inhibitors, and alpha-tocopherol, a clinically potent PKC inhibitor, suppressed the lysoPC-induced NF-kappaB activation. These results indicate that lysoPC regulates NF-kappaB activity in a biphasic manner dependent on its concentrations and incubation time in human endothelial cells and the endothelial PKC activation may in part be involved in the lysoPC-induced NF-kappaB activation. Thus, the time course and the positive and negative biphasic regulatory actions of lysoPC on NF-kappaB activity in endothelial cells might exhibit a unique effect of lysoPC in arterial walls on the different stages of atherosclerosis.

Cells, Cultured↗

PubMed1998

Comparison of thrombolytic therapies with mutant tPA (lanoteplase/SUN9216) and recombinant tPA (alteplase) for acute myocardial infarction.

The fibrinolytic capacity of patients with acute myocardial infarction (AMI) is known to be impaired. The primary regulatory element of the fibrinolytic system is plasminogen activator inhibitor (PAI). It has been previously observed that there are 2 peaks in the plasma PAI level of AMI patients at 4h and 16h after thrombolytic therapy with recombinant tissue plasminogen activator (rtPA). Lanoteplase/SUN9216 is a mutant tPA with a biological half-life longer than that of rtPA. Thrombolytic therapy with mutant tPA or rtPA was carried out consecutively in 21 patients with AMI (8 patients as the mutant tPA group, and 13 patients as the rtPA group). The recanalization time of the mutant tPA group was significantly faster than that of the rtPA group (16.1 +/- 3.9 min vs 39.6 +/- 4.8 min, p<0.01). The PAI activity at 4h after the initiation of thrombolysis was significantly lower in the mutant tPA group than in the rtPA group (8.74 +/- 5.46IU/L vs 26.74 +/- 3.35 IU/L, p<0.01). There was a one mild peak in serial plasma PAI activity levels 24h after the initiation of thrombolysis. The results suggest that thrombolytic therapy with mutant tPA reduced the impairment of fibrinolytic capacity. The mutant tPA gives faster recanalization and lower PAI activity after successful thrombolysis, compared with rtPA.

Aged↗