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Biomedical subjects

K Okazaki

Publications and source records attributed to K Okazaki.

At least 145 records · Page 8Linked to original sources
PubMed1998

Growth inhibition of cultured human Tenon's fibroblastic cells by targeting the E2F transcription factor.

The transcription factor E2F regulates the expression of several genes concerned with cell growth. The ability to inhibit transcription by blocking E2F expression has great potential in the treatment of proliferative disorders. The effect of double-stranded phosphorothioate oligonucleotides containing E2F transcription factor cis element, a so called 'decoy' has examined on the growth of cultured human Tenon's fibroblastic cells. Human Tenon's fibroblastic cells were cultured and challenged by E2F decoy coated with the Hemagglutinating virus of Japan (HVJ) cationic liposomes (HVJ-CL). The outcome was evaluated using fluorescence microscopy, RT-PCR and growth assays. HVJ-CL facilitated the transfer of external oligonucleotides to cultured human Tenon's fibroblastic cells. The E2F decoy, transferred by HVJ-CL, inhibited simultaneously the expression of the mRNAs of several cell cycle related genes such as c-myc, cdc2, proliferative cell nuclear antigen, and dehydrofolate reductase. Entry into S phase was also reduced to 42.7% of the positive control by the E2F decoy. The total increase of DNA at four days was reduced to 59.7% of the positive control by 5 microM and 29.9% by 15 microM of E2F decoy. It is concluded that gene therapy using the E2F transcription factor offers a potential therapeutic modality for the treatment of proliferative disorders such as proliferative vitreoretinopathy and fibrosis following filtering surgery.

Carrier Proteins↗
PubMed1998

Possible role of platelet-activating factor in the in vivo expression of tissue factor in neutrophils.

BACKGROUND: Recently, we demonstrated that neutrophils express tissue factor (TF) in a model of acute obstructive cholangitis (AOC). However, the regulation of TF expression was not clear. In this study, we clarified the role of platelet-activating factor (PAF) in TF expression in neutrophils. MATERIALS AND METHODS: In a model of AOC, intravenous PAF antagonist, (SM-12502, 200 mg/kg) was administered 5 min before sepsis was induced. Normal saline was given as a control. Coagulation parameters and TF activity were monitored for 6 h. Thereafter, the liver was harvested for histological examination. RESULTS: The percentage of neutrophils which stained positive for TF was significantly reduced by SM-12502 (74.9 +/- 19.3% vs 96.3 +/- 2.8%) (P < 0.01). The number of leukocytes infiltrating the liver was also significantly reduced. Coagulation abnormalities, TF activity, and focal necrosis of the hepatocytes were reduced by SM-12502. CONCLUSIONS: SM-12502 inhibits TF expression in neutrophils which have infiltrated the liver sinusoids, reducing the subsequent infiltration of leukocytes. These results suggest that PAF plays an important role in the expression of TF in neutrophils in vivo.

Animals↗
PubMed1998

An attenuation mechanism of Newcastle disease vaccine strain TCND.

To provide information on the mechanism of attenuation of a Newcastle disease vaccine strain, TCND, we compared it with the parental virulent strain California 11,914 (CAL) biologically and genetically. It was found that TCND bore the fusion protein of virulent type, consisting of a pair of dibasic amino acid residues at the cleavage site and was a temperature sensitive (ts) mutant restricted to grow at 41.5 degrees C. Revertants were obtained by prolonged incubation of chicken embryos inoculated with TCND at the nonpermissive temperature. In cultured cells, viral gene transcription and protein synthesis of TCND occurred similarly to those of CAL and the revertants at 41.5 degrees C. Hemadsorption and immunofluorescence assays revealed that cell surface expression of functional hemagglutinin-neuraminidase (HN) of TCND at 41.5 degrees C was lower than that at 35 degrees C. The revertants exhibited lower activity in fusion assay than CAL and recovered virulence to chicken only in part. The results indicate that the ts mutation of TCND in association with the defect of HN glycoprotein transport is a mechanism of the attenuation, and in addition, some other factors such as fusion activity should be involved in the loss of virulence of CAL to chickens.

Amino Acid Sequence↗
PubMed1998

Fusion of influenza virus with the endosomal membrane is inhibited by monoclonal antibodies to defined epitopes on the hemagglutinin.

Epitopes on the hemagglutinin (HA) of A/seal/Massachusetts/1/80 (H7N7) influenza virus were mapped by genetic analysis of variants selected with monoclonal antibodies (MAbs). Electron microscopic studies demonstrated that the sites and the directions to which hemagglutination-inhibiting (HI) MAbs and non-HI MAbs bound were different on the HA molecule. Morphological analysis revealed that HI MAbs blocked attachment of the virus to the cells, while non-HI MAbs did not. Virus particles bound with non-HI MAbs were then found in the intracellular vacuoles. Together with the electron microscopic findings, a fluorescence dequenching assay indicated that non-HI MAbs inhibited the fusion of virus with the intracellular vacuolar membrane. It was thus shown that non-HI neutralizing MAbs did not inhibit attachment of the virus to the host cell receptor, but inhibited the fusion step in intracellular vacuoles. The results support the hypothesis that anti-HA MAbs which lack HI activity neutralize viral infectivity by interfering with the low pH-induced conformational change in the HA molecule, resulting in inhibition of the fusion step in the viral replication process (Kida, H., Yoden, S., Kuwabara, M., Yanagawa, R., 1985. Interference with a conformational change in the HA molecule of influenza virus by antibodies as a possible neutralization mechanism. Vaccine 3, 219-222).

Animals↗
PubMed1998

Alterative expression of the collagenase and adhesion molecules in the highly metastatic clones of human colonic cancer cell lines.

Human colonic carcinoma cell lines, KM12C, KM12SM and KM12L4, were previously established and their in vivo metastatic potentials have been well evaluated. The highly metastatic cell lines KM12SM and KM12L4 were derived from the parental low metastatic cell line KM12C in vivo. To evaluate the metastatic behavior of these cell lines in vitro, we examined colony formation on monolayers of the pulmonary arterial endothelial (CPAE) cells. On day 4, the highly metastatic cell lines showed an approximately 2-fold increase in number of colonies on CPAE cell monolayers relative to the parental KM12C cell line. To investigate what evidence is correlated with their metastatic and invasive abilities, Northern blot analysis and flow cytometry were performed in all cell lines. According to the results of Northern blot analysis, the levels of matrix metalloproteinase (MMP)-2 and c-met mRNA expression were increased in highly metastatic cell lines as compared with the parental cell line. We also examined the cell-surface expression of several adhesion molecules by flow cytometry. The levels of expression of sialyl Lewisa antigen (sLe(a)) in KM12SM and KM12L4 were twice higher than that in KM12C. However, the levels of expression of E-cadherin in KM12SM and KM12L4 were decreased to half that in KM12C. The alterative expression of the collagenase and adhesion molecules might contribute to their metastatic/invasive abilities of these cell lines both in vivo and in vitro.

Antigens, CD↗
PubMed1998

Involvement of barium-sensitive K+ channels in endothelium-dependent vasodilation produced by hypercapnia in rat mesenteric vascular beds.

1. We examined the vasodilatory effect of hypercapnia in the rat isolated mesenteric vascular bed. The preparation was perfused constantly (5 ml min(-1) with oxygenated Krebs-Ringer solution, and the perfusion pressure was measured. In order to keep the extracellular pH (pHe) constant (around 7.35) against a change in CO2, adequate amounts of NaHCO3 were added to Krebs-Ringer solution. 2. In the endothelium intact preparations, an increase in CO2 from 2.5% to 10% in increments of 2.5% decreased the 10 microM phenylephrine (PE)-produced increase in the perfusion pressure in a concentration-dependent manner. Denudation of the endothelium by CHAPS (3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulphonate) (5 mg l(-1), 90 s perfusion) abolished the vasodilatory effect of hypercapnia. 3. An increase in CO2 from 5% to 10% reduced the increases in the perfusion pressure produced by 10 microM PE and 400 nM U-46619 by 48% and 44%, respectively. NG-monomethyl-L-arginine (100 microM) and indomethacin (10 microM) did not affect the vasodilatory effect of hypercapnia, whereas the vasodilatory response of the preparation to hypercapnia disappeared when the preparation was contracted by 60 mM K+ instead of PE or U-46619. 4. The vasodilatory effect of hypercapnia observed in the PE- or U-46619-precontracted preparation was affected by neither tetraethylammonium (1 mM), apamin (500 microM), glibenclamide (10 microM), nor 4-aminopyridine (1.5 mM). On the other hand, pretreatment with Ba2+ at a concentration of 0.3 mM abolished the hypercapnia-produced vasodilation. 5. An increase in the concentration of K+ in Krebs-Ringer solution from 4.5 mM to 12.5 mM in increments of 2 mM reduced the PE-produced increase in the perfusion pressure in a concentration-dependent manner. Pretreatment of the preparations with not only Ba2+ (0.3 mM) but also CHAPS abolished the vasodilatory effect of K+. 6. The results suggest that an increase in CO2 produces vasodilation by an endothelium-dependent mechanism in the rat mesenteric vascular bed. The membrane hyperpolarization of the endothelial cell by an activation of the inward rectifier K+ channel seems to be the mechanism underlying the hypercapnia-produced vasodilation. Neither nitric oxide nor prostaglandins are involved in this response.

Animals↗
PubMed1998

Efficacy of total colonoscopy with a transparent cap in comparison with colonoscopy without the cap.

BACKGROUND AND STUDY AIMS: In spite of scrupulous inspection during routine colonoscopy, small lesions behind the semilunar folds can be situated in blind spots, where they are easily overlooked. The aim of this study was to evaluate the efficacy of total colonoscopy with a transparent cap in identifying such lesions, in comparison with colonoscopy without the cap. PATIENTS AND METHODS: In 24 patients with colorectal polyps, tandem colonoscopic procedures were carried out on the same day in random order, first without a transparent cap and then with the cap (without-to-with), or first with the cap and then without the cap (with-to-without). The time required for intubation as far as the cecum, the number of polyps detected, and procedure-related complications were recorded. The frequencies of terminal ileal intubation and retroflexion within the rectum were also recorded. RESULTS: Total colonoscopy was carried out in all of the patients without any complications. Colonoscopy with a transparent cap ensured good visual fields during insertion and withdrawal of the colonoscope. There were no significant differences in the intubation time to the cecum or in the frequency of terminal ileal intubation between the two procedures. The miss rate for polyps was 15% in without-to-with tandem colonoscopies, and zero in with-to-without procedures (P = 0.0125). The diameter of all the missed polyps except for one lesion (8 mm) was less than 5 mm. Retroflexion within the rectum was more difficult using the colonoscope with the cap (P < 0.0001), and was successful in only one case using the cap. CONCLUSIONS: Total colonoscopy with a transparent cap allows inspection of the blind area of the colonic mucosa behind the semilunar folds, with good visual fields. This method is potentially useful for both screening and diagnostic purposes.

Adult↗
PubMed1998

Downregulation of gastric mucin gene expression and its biosynthesis by dexamethasone in the human.

The effect of corticosteroids on the release and biosynthesis of gastric mucin remains unclear. We studied the effects of dexamethasone on biosynthesis of mucin and MUC1 gene expression in the human stomach in vitro. Gastric mucosal specimens, obtained from six subjects at gastrectomy, were cultured with various concentrations of dexamethasone. Biosynthesis of mucin was studied by labeling gastric mucosa for 2 h with [3H]-glucosamine. After purification of mucin by CsCl gradient centrifugation, radioactivity of intra- and extracellular samples was counted. MUC1 gene expression was studied by Northern and dot-blot analysis using a cDNA encoding human gastric mucin gene MUC1. The dexamethasone treatment decreased mucin secretion from the isolated mucosa in a time- and concentration-dependent manner, with maximal inhibition of secretion (32+/-6%) observed after 8 h and 10(-5) M. Dexamethasone treatment also decreased MUC1 levels (28+/-9%). The inhibitory effect was also observed in carbachol-evoked secretion. These findings suggest that a decrease in mucin biosynthesis by corticosteroids may be involved in steroid-induced gastric mucosal damage.

Adult↗
PubMed1998

Temperature-sensitive effects of potassium channel openers on isolated guinea pig myocardium and aorta.

The effects of K+ channel openers, NIP-121, cromakalim, and pinacidil, on isolated myocardium and aorta were investigated at two different temperatures, 23 degrees C and 37 degrees C. In right ventricular myocardium, NIP-121 shortened the action-potential duration with little influence on other action-potential parameters at 37 degrees C, but not at 23 degrees C. In whole-cell clamped ventricular myocytes, NIP-121 induced a glibenclamide-sensitive outward current at 37 degrees C but not at 23 degrees C. No difference in tissue adenosine triphosphate (ATP) concentration was detected between ventricular myocardia incubated at 37 degrees C and at 23 degrees C. In aortic preparations precontracted with norepinephrine, NIP-121, cromakalim, and pinacidil produced endothelium-independent relaxation at 37 degrees C, which was antagonized by glibenclamide. The vasorelaxant effects were greatly reduced at 23 degrees C. Thus we demonstrated that the effects of K+ channel openers on the myocardium and vascular smooth muscle are temperature sensitive.

Action Potentials↗
PubMed1998

Multiple pancreatic masses associated with autoimmunity.

A 59-year-old woman was detected to have a high titer of serum gamma-globulin, positive antinuclear antibody and multiple pancreatic masses. In the course of 1 yr, Sjögren's syndrome developed, and her pancreatic masses spread diffusely and compressed the main pancreatic duct. A pancreatic biopsy by an exploration of the abdomen showed that many CD4 positive T-lymphocytes had infiltrated to the ducts and acinar cells expressing HLA-DR antigens. This suggested a diagnosis of autoimmune-related pancreatitis. She was treated with oral prednisolone, and a marked improvement of the above abnormal findings followed. In this report, a case of autoimmune-related multiple pancreatic masses associated with Sjögren's syndrome is presented, and a possible mechanism is discussed.

Administration, Oral↗
PubMed1998

Antilactoferrin antibodies in autoimmune liver diseases.

OBJECTIVE: Lactoferrin, an immunoregulatory protein in mucosal secretions, is one of the target antigens to perinuclear antineutrophil cytoplasmic antibodies (P-ANCAs). Circulating lactoferrin is cleared in the liver, but little is known about the implication of lactoferrin in hepatic inflammation. To evaluate the implication of immunological response to lactoferrin, we examined antilactoferrin antibodies in autoimmune liver diseases. METHODS: Fourteen patients with primary biliary cirrhosis (PBC), 14 with autoimmune hepatitis (AIH), five with autoimmune cholangitis (AIC), six with chronic hepatitis C, and five with chronic hepatitis B were studied. We evaluated autoantibodies to lactoferrin in the sera of the patients by the Western Immunoblotting method. RESULTS: Sera of five of the 14 patients (35.7%) with PBC, four of the 14 patients (28.6%) with AIH, and five of the five patients (100%) with AIC contained autoantibodies to human lactoferrin, but none with hepatitis B or C had them. The higher prevalence of serum antibodies to human lactoferrin was shown to be higher in patients with AIC than with hepatitis B (p < 0.01), hepatitis C (p < 0.01), PBC (p < 0.05), and AIH (p < 0.05). CONCLUSION: Lactoferrin located in bile ducts and liver cells is one of the candidates of target antigens in autoimmune liver diseases, especially in AIC.

Adolescent↗
PubMed1998

Novel factor highly conserved among eukaryotes controls sexual development in fission yeast.

In the fission yeast Schizosaccharomyces pombe, the onset of sexual development is controlled mainly by two external signals, nutrient starvation and mating pheromone availability. We have isolated a novel gene named rcd1+ as a key factor required for nitrogen starvation-induced sexual development. rcd1+ encodes a 283-amino-acid protein with no particular motifs. However, genes highly homologous to rcd1+ (encoding amino acids with >70% identity) are present at least in budding yeasts, plants, nematodes, and humans. Cells with rcd1+ deleted are sterile if sexual development is induced by nitrogen starvation but fertile if it is induced by glucose starvation. This results largely from a defect in nitrogen starvation-invoked induction of ste11+, a key transcriptional factor gene required for the onset of sexual development. The striking conservation of the gene throughout eukaryotes may suggest the presence of an evolutionarily conserved differentiation controlling system.

Amino Acid Sequence↗
PubMed1998

Bactericidal action of 4,4'-(alpha,omega-polymethylenedithio)bis-(1-alkylpyridinium iodide)s.

Bactericidal action of novel bis-quaternary ammonium compounds (bis-QACs), 4,4'-(alpha,omega-polymethylenedithio)bis(1-alkylpyridinium iodide)s (4DTBP-m,n) was studied. The bactericidal activity of 4DTBP-m,n in water was not affected by the molecular hydrophobicity unlike general mono-QAC, N-dodecylpyridinium iodide (P-12), while the bacteriostatic activity in the medium was reduced with their hydrophobicity. This result suggested that the hydrophobic materials in the medium interact with 4DTBP-m,n and cover their active moiety. Since the bactericidal activity using the measurement system supplemented with peptone was influenced by the molecular hydrophobicity, this speculation was supported. The plots of the bacteriostatic activities of 4DTBP-m,n against the surface hydrophobicities of various bacteria accord to the straight line as in the case of P-12. The slope of the line of 4DTBP-6,12 was comparatively smaller than that of 4DTBP-6,8, indicating that the compounds having longer alkyl group tend to reduce their activities against the bacteria with hydrophobic cell surface because of their interaction with the hydrophobic materials. The novel bis-QACs have an ability to liberate rapidly and abundantly the turbid materials from cells, that is, a bacterioclastic activity. The bacterioclastic activity of P-n was influenced by the length of alkyl group, while 4DTBP-6,n had almost the same activity regardless of its length. Observation by scanning electron microscope (SEM) revealed that 4DTBP-6,8 fatally damaged Escherichia coli cells, and that the morphological alteration of the cells caused by the bis-QAC was greatly different from that of the usual QAC. Therefore, the effective bacterioclastic action, and excellent bactericidal action is due to the unique dimeric structure of 4DTBP-m,n.

Anti-Bacterial Agents↗
PubMed1998

Detection of antitumor promoting activity in Raji cells carrying Epstein-Barr virus genome by immunoblotting analysis.

Extract of Raji cells treated with sodium n-butyrate (1 mM) and a tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA, 40 ng/ml), was analyzed by immunoblotting using ten human sera with different antibody titers against Epstein-Barr virus early antigens. Two human sera reacted with one induced polypeptide of 48 kDa and its induction was inhibited by curcumin (4 micrograms/ml), an antitumor promoter from turmeric. A mouse antiserum against P3HR-1 cells treated with TPA and sodium n-butyrate also detected the 48-kDa polypeptide in Raji cells treated with TPA at concentrations of 2.5 to 80 ng/ml. These results indicate that the immunoblotting analysis can be used in a confirmation test for detection of antitumor promoting activity.

Animals↗
PubMed1998

Hepatic and splenic sarcoidosis evaluated by multiple imaging modalities.

We present a case of hepatosplenic sarcoidosis. A 51-year-old Japanese male, who was diagnosed to have sarcoidosis 4 years previously, was presented to our hospital because of dry cough and anorexia with weight loss. He had tender hepatosplenomegaly. A dynamic abdominal computed tomography (CT) revealed multiple small low-density areas in both liver and spleen, as well as in magnetic resonance imaging (MRI). The laparoscopic photographs showed many small whitish nodules surfacing on the liver and several tumorous nodules on the spleen. Multiple imaging modalities including dynamic CT and MRI are valuable for detecting focal hepatic and splenic lesions of sarcoidosis.

Biopsy↗