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Biomedical subjects

M Mizuno

Publications and source records attributed to M Mizuno.

At least 271 records · Page 15Linked to original sources
PubMed1995

Redox regulation of NF-kappa B DNA binding activity by dihydrolipoate.

NF-kappa B transcription factor regulates a wide variety of cellular and viral genes including the human immunodeficiency virus type 1. Here, we demonstrate that dihydrolipoate/alpha-lipoate redox couple which is a cofactor for mitochondrial dehydrogenases reactions, influences the DNA binding activity of NF-kappa B. The elimination of dithiothreitol in the electrophoretic mobility shift assay protocol resulted in the inability to detect DNA binding activity of activated NF-kappa B. The DNA binding activity was restored by the addition of dihydrolipoate in the binding reaction mixture. Inhibition of NF-kappa B DNA binding activity by in vitro exposure to a sulfhydryl oxidizing agent, diamide was also blocked by dihydrolipoate. In contrast, the addition of the oxidized form, alpha-lipoate inhibited the NF-kappa B DNA binding activity. Coincidentally, preincubation of Jurkat cells with dihydrolipoate potentiated and alpha-lipoate inhibited the okadaic acid-induced NF-kappa B activation as detected by assessing its DNA binding activity. These results suggest the redox exchange between lipoate and NF-kappa B molecules. Furthermore, since the inhibition of AP-1 DNA binding activity by diamide was also blocked by dihydrolipoate, this natural reductant may participate in the redox regulation of transcription factors by enhancing the DNA-protein interactions.

Base Sequence↗
PubMed1995

[The effectiveness of interferon-beta against glioma cells and its augmentation of growth inhibitory effect by transfection of its gene].

The mortality and morbidity of patients with malignant glioma is not satisfactory, although the survival time is prolonged by several adjuvant therapies. In order to increase the survival time, various studies have been undertaken. In the present article, at first we discuss the effectiveness of the single and/or combined therapy of interferon-beta. Although a synergistic effects with radiation is noted in nitrosoureas and interferon-beta, and it is the most effective treatment for malignant glioma at present, it is still necessary to continue to search for an effective strategy to prolong survival of the patients. To improve the interferon-beta cytokine therapy, we have studied liposome mediated transfection of cytokine genes to control glioma cells. For this purpose, human beta-interferon gene entrapped in liposome was transfected into glioma cells and the growth inhibitory effect was observed. Successful secretion of interferon-beta and remarkable suppression effect to the glioma cells was demonstrated and this effect was enhanced by conjugating with monoclonal antibody G-22 on the surface of liposome. These results suggest that interferon-beta gene transfection by the use of liposome coupled with monoclonal antibody might become a useful technique for gene therapy of malignant glioma.

Antibodies, Monoclonal↗
PubMed1994

Signal transduction for nuclear factor-kappa B activation. Proposed location of antioxidant-inhibitable step.

Reactive oxygen species are thought to be messengers for nuclear factor (NF)-kappa B activation because its activation can be abrogated by antioxidants. However, this study identifies, for the first time, NF-kappa B activators that are insensitive to antioxidants. NF-kappa B activation that is induced by either calyculin A or okadaic acid (inhibitors of serine/threonine protein phosphatases 1 and 2A) is not blocked by N-acetylcysteine or dihydrolipoate in Jurkat and U937 cells. Nonetheless, these antioxidants block induction by TNF-alpha, lymphotoxin, and PMA. Unlike okadaic acid and calyculin A, neither TNF-alpha, lymphotoxin, nor PMA inhibited activities of phosphatases 1 and 2A. NF-kappa B activation induced by okadaic acid or calyculin A was not blocked by a myosin light chain kinase inhibitor, but was prevented by a protease inhibitor. The mitochondrial inhibitor, rotenone, also inhibited NF-kappa B activation by calyculin A; however, this inhibition was accompanied by a depletion of cellular ATP. These results suggest that 1) phosphatase inhibitors either target a component of signal transduction, which occurs downstream to an antioxidant-sensitive step or use distinct signaling pathways; 2) inhibition of phosphatases 1 and 2A is not a step in the pathway of TNF-alpha-, lymphotoxin-, or PMA-induced NF-kappa B activation; 3) myosin light chain kinase does not participate in NF-kappa B activation; and 4) activation of NF-kappa B by phosphatase inhibitors is controlled by proteases.

Antioxidants↗
PubMed1994

Distribution profiles of GC content around the translation initiation site in different species.

We have analyzed the distribution of guanine-cytosine (GC) content around the translation initiation site in genomic DNA sequences of different species. A set of sequences belonging to one species is aligned at the translation initiation site, and the average GC content is calculated for 100 base windows over a range of 500 bases each for upstream and downstream region. Consistent with previous observations that coding regions are more GC-rich than non-coding regions, we observe a jump in the GC content at the translation initiation site, except for vertebrate sequences. It was also found that the overall shape of the GC content profile is similar within each organism group even though the average GC contents can be very different. Furthermore, by examining different profiles for different species, we have found a negative correlation between the average GC content and the jump size at the translation initiation site. Apparently, more AT-rich genomes, which tend to lack macroscopic mosaic structures, exhibit more marked differences in the GC content at the microscopic level.

Animals↗
PubMed1994

Differences in immunomodulating effects between wild and cultured Panax ginseng.

The different effects between wild and cultured Panax ginseng on immunological activity were investigated. The extracts of hot water soluble fraction from wild Panax ginseng showed the mitogenic activity to lymphocytes but that from cultured Panax ginseng did not. The mitogenic activity of wild Panax ginseng (100 micrograms/well) was almost equal to Concanavalin A (0.1 microgram/well) which was well-known as one of T cell mitogens. The percentages of Thy 1.2-(pan T cells), L3T4-(helper T cells) and Lyt2-(cytotoxic T cells) positive cell population were significantly increased in the mice orally administered hot water soluble fraction from wild Panax ginseng as compared to control by 31.2, 17.9 and 30.1 percent, respectively.

Adjuvants, Immunologic↗
PubMed1994

Effects of alpha-lipoic acid and dihydrolipoic acid on expression of proto-oncogene c-fos.

The transcription factor AP-1 is an important human mediator of the cellular response to serum, growth factors, and phorbol esters such as 12-O-tetradecanoyl-phorbol-13 acetate (TPA). The AP-1 complex consists of distinct protein heterodimers encoded by the proto-oncogene c-fos and c-jun mRNA whose gene expression can be induced by TPA, cyclic AMP and growth factors. Recent findings suggest an involvement of reactive oxygen species in the pathway of TPA and protein kinase C leading to expression of c-fos and c-jun mRNA. To investigate the role of reactive oxygen species we studied the effects of alpha-lipoic acid and dihydrolipoic acid (natural thiol antioxidants) on the expression of c-fos mRNA in human Jurkat T cells. When cells were preincubated with dihydrolipoic acid (0.2 mM) the expression of c-fos mRNA was suppressed at 30 min after stimulation of TPA (0.5 microM) whereas in the case of preincubation of alpha-lipoic acid (0.2 microM), the expression was enhanced at 30 min. These studies support the idea that superoxide anion radical plays a role in the expression of c-fos mRNA.

Base Sequence↗
PubMed1994

The significance of the cervical soft disc herniation in the ossification of the posterior longitudinal ligament.

The significance and role of cervical soft disc hernia in ossification of the posterior longitudinal ligament were investigated based on 54 surgical cases. The types of ossification of the posterior longitudinal ligament were divided into three sub-types: segmental, continuous, and mixed types. In the current series, there were 29 segmental type, 12 continuous type, and 13 mixed type. In the 29 segmental type, 23 patients had accompanying cervical disc hernias (79%). In the 12 continuous type, only 2 patients (17%), and in the 13 mixed type, 5 patients (33%), had accompanying disc hernias. According to the current study, an essential difference exists between the segmental type and the continuous or mixed types. In addition, the current result seems to indicate that, at least in the segmental type, disc herniation is not the promoting or initiating factor of ossification of the posterior longitudinal ligament, but that, in these cases, the fragility of the posterior longitudinal ligament may increase the chance of a disc hernia.

Adult↗
PubMed1994

Serum hepatitis C virus RNA level as a predictor of subsequent response to interferon-alpha therapy in Japanese patients with chronic hepatitis C.

Serum hepatitis C virus (HCV) RNA level has been shown to be a good predictor of subsequent response to interferon-alpha (IFN) therapy in US patients in whom genotype 1a/1b are both predominant. To determine whether serum HCV RNA level is a predictor of subsequent response to IFN in Japanese patients or not, appropriately collected pre-IFN therapy serum samples from 35 Japanese patients with chronic HCV infection were studied. Serum HCV RNA level and HCV genotype were determined and correlated with the subsequent response to IFN. Response to IFN was defined by serum alanine transaminase level: complete and sustained response (n = 15), complete response followed by relapse (n = 10), and no response (n = 10). Patients with complete and sustained response had lower pre-IFN serum HCV RNA level (median: RT-PCR+, bDNA-) compared to the complete response to relapse group (median: 5.25 x 10(6) genome equivalent/ml [eq/ml], P < 0.001) and the no response group (median: 10.63 x 10(6) eq/ml, P < 0.001). Seven (46.7%) of the complete and sustained response patients had HCV genotype 2a and three patients had a mixture of genotypes 1b and 2a. In contrast, all 10 patients in the complete response to relapse group had genotype 1b whereas 8 of 10 patients in the non-response group had genotype 1b and 2 had genotype 2b. The patients with HCV genotype 2a had lower serum HCV RNA level than those with 1b (P = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Temporal pattern sensitivity of long-term potentiation in hippocampal CA1 neurons.

High-frequency electrical stimulation in the hippocampus leads to an increase in synaptic efficacy that lasts for many hours. This long-term potentiation (LTP) of synaptic transmission is presumed to play a crucial role in learning and memory in the brain. However, the frequency of stimulation generally used to obtain LTP is beyond the normal physiological range of activity of hippocampal neurons. We found that LTP can be induced by an electrical stimulation whose frequency is comparable to that of the naturally occurring firing activity of hippocampal neurons if the stimulating pulse-interval train has a special time structure. In the present experiment, we compared the magnitude of LTP induced by the four types of stimuli which have the same pulse number and the same mean frequency but different time structure in interstimulus intervals. One type of stimuli has regular intervals, and this served as a control stimulus. In the other three types of stimuli, the adjacent interstimulus interval had the following statistical properties: in type 1, their correlations are positive; in type 2, negative; and in type 3, independent. The magnitude of LTP induced by these four types of stimuli showed clear order relationships: type 3/type 1 >> control > type 2. Detailed analysis of the evoked potential during a period of temporal pattern stimulation revealed that the amplitude of the population spikes of repetitive firing, especially of the second and third population spikes, had the same order relationship as the LTP.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Amino-5-phosphonovalerate↗
PubMed1994

Growth inhibition of subcutaneously transplanted human glioma by transfection-induced tumor necrosis factor-alpha and augmentation of the effect by gamma-interferon.

Using subcutaneous solid tumors produced by U251-MG human glioma cells, we studied the in vivo transfection of the cells with the tumor necrosis factor-alpha (TNF-alpha) gene delivered by means of liposomes. When the tumor had become 7 mm in diameter, liposomes with entrapped TNF-alpha gene were injected into the center of the subcutaneous tumor. We found that mRNA of transfection-induced TNF-alpha, which was expressed in the tumor tissue, was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) method and its protein was demonstrated by enzyme-linked immunoassay. Growth of the tumor was inhibited when the injection was carried out five times at every other day. The growth-inhibitory effect by transfection-induced TNF-alpha was much remarkable as compared with exogenous TNF-alpha and the effect was enhanced by the intraperitoneal injection of gamma-interferon (IFN-gamma) 12 h prior to intratumoral injection of the liposomes.

Animals↗
PubMed1994

Efficient transfection of human interferon-beta gene to human glioma cells by means of cationic multilamellar liposomes coupled with a monoclonal antibody [corrected].

We have been devoting our efforts to develop the useful liposomes that have high potentials of gene transfer and we aim human gene therapy for malignant glioma with cytokine genes. In our previous study, we prepared our original reverse-phase evaporation vesicles (REV) by an improved procedure of reverse-phase evaporation method. However, this procedure was very complicate. In this paper, a simple procedure for the preparation of cationic multilamellar vesicles (MLV) was introduced, and efficient expression and growth-inhibitory effect of MLV with entrapped human interferon-beta gene to glioma cells was comparable to that obtained with REV. Considering the present experiments, MLV seem to be more preferable for clinical application.

Brain Neoplasms↗
PubMed1994

Importance of cytotoxic T lymphocytes in the rejection of transplanted hepatocellular carcinoma.

Fischer rats became resistant to syngeneic hepatocellular carcinoma (FAA-HTC1) cells on repeated sensitization with mitomycin C-treated FAA-HTC1 cells. In contrast, FAA-HTC1 cells injected into the liver killed normal control Fischer rats within 2 months. Histopathological studies revealed massive accumulation of mononuclear cells in the tumor tissues of sensitized rats that rejected syngeneic FAA-HTC1 cells, whereas very few mononuclear cells were found in the tumor tissues of control rats. Cell populations infiltrating the tumor tissues were identified by flow cytometric analysis. Mononuclear cells found within the regressing tumors of the sensitized rats were identified as mostly T cells, and two-thirds of these T cells were CD8-positive. Compared with the activity in control rats, the killer activity of mononuclear cells infiltrating tumors was significantly increased in the sensitized rats 7 days after tumor inoculation. Depletion of CD8(+) T cells significantly reduced the cytotoxicity of mononuclear cells infiltrating tumors obtained from sensitized rats. In contrast, depletion of CD16(+) cells reduced the cytotoxicity of mononuclear cells infiltrating tumors obtained from both control and sensitized rats. Furthermore, the CD16(+) cell-depleted fraction of mononuclear cells infiltrating tumors showed significant cytotoxicity against FAA-HTC1 cells, but failed to show cytotoxicity against other syngeneic tumor cells or allogeneic hepatoma cells.

Animals↗
PubMed1994

Immunohistochemical study of the distribution of intercellular adhesion molecule-1 and lymphocyte function-associated antigen-1 in chronic type B hepatitis.

The expression of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1) in the livers of 11 patients with chronic hepatitis B was studied immunohistochemically by light and electron microscopy to clarify the role of these adhesion molecules in tissue damage in chronic hepatitis B. On hepatocytes, ICAM-1 expression was confined to the bile canalicular surface when the liver inflammation was mild. In contrast, when the liver inflammation was severe, ICAM-1 was distributed on the entire surface of the hepatocyte, including the sinusoidal and lateral membranes; lymphocytes which were mostly positive for LFA-1, were often observed invading deeply among these hepatocytes. The degree of ICAM-1 expression on the hepatocytes was also related to the expression of HLA class 1 antigen. In liver showing diffuse expression of ICAM-1 on the hepatocytes, strong expression of HLA class 1 antigen was observed, and amounts of HBV in the liver were decreased. Diffuse expression of ICAM-1 and HLA class 1 antigen was mostly observed after acute exacerbation of liver inflammation. These results suggest that the ICAM-1/LFA-1 pathway is involved in the immunological mechanism responsible for liver cell damage in chronic hepatitis B.

Cell Adhesion Molecules↗