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Biomedical subjects

S Okubo

Publications and source records attributed to S Okubo.

At least 73 records · Page 4Linked to original sources
PubMed1994

[Inhibition of the infectivity of influenza virus by black tea extract].

We determined whether black tea extract inhibits the infectivity of influenza virus to mice. When mice were inoculated intranasally with 10(5.3) PFU influenza viruses (10(1.3) LD50), their body weight decreased and all died within 10 days. Whereas, when mice were inoculated i.n. with the mixture of influenza viruses and 2% (w/w) black tea extract, 5 min after mixing, all mice showed normal body-weight increase and survived. Neutralizing antibody to influenza virus was not detected in nine of 10 survived mice. The results indicate that black tea extract at beverage concentration (2% w/w) inhibits almost completely the infectivity of influenza virus to mice and that in vivo reversion of the tea-inactivated influenza virus does not occur.

Animals↗
PubMed1994

Effective monitoring of concentrations of ofloxacin in saliva of patients with chronic respiratory tract infections.

To ascertain whether monitoring of the concentrations of ofloxacin in saliva during a course of treatment is more suitable and safer than that of its levels in blood, we simultaneously monitored its concentrations in three body fluids (blood, saliva, and expectorated sputum) after a 300-mg administration in 18 patients with chronic respiratory infection. The mean (+/- standard error of the mean) half-lives derived from the three drug level-time relationships were similar: 6.04 +/- 0.58 h for serum, 6.34 +/- 0.63 h for sputum, and 6.61 +/- 0.65 h for saliva. The mean peak concentration (4.06 to 4.53 micrograms/ml) did not differ at the three sites, but the times taken to reach peak concentration in saliva and sputum (3.17 +/- 0.46 h) were significantly longer than that in serum (2.22 +/- 0.28 h). The ratios of the concentrations in saliva and sputum to the concentration in serum increased during the first 2 h and reached 1.0 between 2 and 8 h after administration. They rose above 1.0 16 h after administration: 1.14 +/- 0.11 for saliva and 1.19 +/- 0.10 for sputum. The concentration-time relationship for sputum corresponded closely with the concentration-time relationship for saliva, and an overall significant correlation between the concentrations in sputum and saliva was obtained (P < 0.01). These results suggest that monitoring concentrations in saliva may be more valid, as well as less invasive, than monitoring of the levels in blood for ensuring that the drug concentration reaches its therapeutic level in bronchial secretions.

Adult↗
PubMed1994

Binding of Legionella pneumophila to macrophages increases cellular cytokine mRNA.

Infection of macrophages with Legionella pneumophila induces formation of interleukin 1 beta (IL-1 beta), but the molecular basis of this is not understood. Binding of bacteria to macrophage surfaces is the first step in an infection process. Therefore, we examined whether this step was sufficient to increase the cellular level of mRNAs for IL-1 beta and other cytokines. To assess the effect of binding of L. pneumophila on the steady-state levels of cytokine mRNAs, cultures of thioglycolate-elicited macrophages from L. pneumophila-susceptible A/J mice were treated with cytochalasin D and infected with L. pneumophila and the total RNA was extracted for analysis by reverse transcription-PCR with primers for IL-1 alpha, IL-1 beta, IL-6, tumor necrosis factor alpha, granulocyte macrophage colony-stimulating factor, and beta interferon (IFN-beta). L. pneumophila treatment increased the cellular steady-state mRNA levels of all cytokines except IFN-beta. To determine the specificity of this effect, macrophage cultures were treated with cytochalasin D and either bacterial lipopolysaccharide, bovine serum albumin-sensitized latex, Salmonella typhimurium, or Escherichia coli. Lipopolysaccharide treatment increased all mRNAs, bovine serum albumin-sensitized latex had no significant effect, and treatment with S. typhimurium or E. coli increased all mRNAs except that of IFN-beta. These results suggested that the binding of gram-negative bacteria to the macrophage surface was sufficient to induce a unique pattern of cytokine mRNAs. Additional studies that examined the characteristics of the bacterial ligands involved indicated involvement of both heat-labile and heat-stable surface ligands.

Animals↗
PubMed1994

Differentiation between human immunodeficiency virus type 1 (HIV-1) and HIV-2 isolates by nonradioisotopic reverse transcriptase-typing assay.

We tested whether human immunodeficiency virus type 1 (HIV-1) could be differentiated from HIV-2 by a reverse transcriptase (RT)-typing assay that measured the reduction of enzyme activity owing to specific antibody. RT-inhibiting antibody was examined for HIV type specificity by a new nonradioisotopic RT assay. Antibodies from four rabbits immunized with recombinant HIV-1 RT and from 23 HIV-1-seropositive individuals all specifically inhibited the enzyme activities of two HIV-1 strains (LAV-1 and GH-3), three zidovudine-resistant HIV-1 mutants, and a recombinant HIV-1 RT. However, none of these antisera affected the activities of six HIV-2 strains (GH-1, GH-2, GH-4, GH-5, GH-6, LAV-2ROD), Rous-associated virus type 2, and DNA polymerase I from Escherichia coli. In contrast, HIV-2 antibody from a rabbit immunized with disrupted GH-1 virions blocked the enzyme activities of the six HIV-2 strains but not those of the three HIV-1 strains, Rous-associated virus type 2, or DNA polymerase I. These results indicate that the antigenic domains of HIV-1 and HIV-2 RTs recognized by their inhibiting antibodies are distinct from each other and are highly conserved. Clinical HIV isolates from 18 HIV-1-seropositive individuals and 3 HIV-2-seropositive Ghanaian individuals were identified as HIV-1 and HIV-2, respectively, by the nonradioisotopic RT-typing assay.

Antibodies, Viral↗
PubMed1993

Calponin phosphatase from smooth muscle: a possible role of type 1 protein phosphatase in smooth muscle relaxation.

Smooth muscle myosin bound phosphatase (MBP) purified from chicken gizzard, which is a holoenzyme of type 1 delta protein phosphatase and dephosphorylated intact myosin, catalyzed the dephosphorylation of calponin phosphorylated by protein kinase C (PK-C). The Km of MBP for calponin was 0.6 microM and the Vmax was 350 nmol/min/mg. All of the multiple sites of phosphorylation by PK-C of calponin were completely dephosphorylated by MBP. Functionally, calponin dephosphorylated by MBP recovered its inhibitory effect on the actin-activated Mg(2+)-ATPase activity of myosin. Therefore, these results suggest that a type 1 delta protein phosphatase causes relaxation of smooth muscle by the dephosphorylation not only of myosin but also of calponin.

Animals↗
PubMed1993

Addition of serum from patients with collagen diseases increases to cultured human endothelial cells production and release of von Willebrand factor.

The addition of sera from patients with collagen diseases, particularly those with vascular complications, to the supernatant of cultured vascular endothelial cells (EC) in vitro significantly increased the surface and intracellular amounts of von Willebrand factor antigen (vWF:Ag) compared with results obtained with sera from normal healthy subjects. Peak levels of vWF:Ag occurred after 24 h of in vitro culture. Moreover, the amounts of vWF:Ag secreted into the EC supernatant with patient serum added were significantly higher than the amounts secreted into EC supernatant with control serum added, even after 48 h of in vitro culture. Levels of large and intermediate multimers (LIM) of von Willebrand factor (vWF) increased in EC supernatant exposed to serum from patients with collagen diseases as compared with levels in supernatant exposed to serum from normal controls, whereas no significant differences were detected overall between adding the plasma of patients and of normal subjects. In addition, C-reactive protein (CRP) induced a time- and dose-related release of vWF:Ag from EC, while glucocorticoid did not effect the release of vWF:Ag from EC. These results suggest that the sera of patients with collagen diseases, particularly those with vascular complications, stimulate the production and release of LIM of vWF from EC.

C-Reactive Protein↗
PubMed1993

Inhibition of the infectivity of influenza virus by tea polyphenols.

(-)Epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) (1-10 microM) inhibited the infectivity of both influenza A virus and influenza B virus in Madin-Darby canine kidney (MDCK) cells in vitro. Study by electron microscope revealed that EGCg and TF3 (1 mM) agglutinated influenza viruses as well as did antibody, and that they prevented the viruses from adsorbing to MDCK cells. EGCg and TF3 more weakly inhibited adsorption of the viruses to MDCK cells. EGCg and TF3 (1-16 microM) also inhibited haemagglutination by influenza viruses. These findings suggest that tea polyphenols bind to the haemagglutinin of influenza virus, inhibit its adsorption to MDCK cells, and thus block its infectivity.

Animals↗
PubMed1993

[Non-radioisotopic reverse transcriptase assay using biotin-11-deoxyuridine-triphosphate and a primer-immobilized microtiter plate: application for detection and identification of isolated retroviruses from HIV-1-seropositive hemophiliac patients].

Non-radioisotopic reverse transcriptase assay (Non-RTA) was successfully applied for detection and identification of the retroviruses isolated from peripheral mononuclear cells from eight HIV-1-seropositive hemophiliac patients. Of 40 samples, 36 (90%) were consistent in detection between Non-RI and RI RTA. Four samples which showed RT activities slightly above the cutoff level of RI RTA were not detected by Non-RI RTA. Non-specific RT-inhibitors in the culture supernatant decreased the sensitivity of Non-RI RTA more significantly than that of RI RTA. It was demonstrated that higher concentrations (> 20%) of fetal calf serum in RPMI-1640 culture medium inhibited the hybridization of poly rA template with immobilized primer, resulting in reducing the sensitivity of Non-RI RTA. Then we identified the isolated retroviruses using specific RT-inhibiting (RTI) antibodies against HIV-1 and HIV-2. HIV-1 RTI antibody specifically inhibited RTs of isolated retroviruses and HIV-1 strain, LAV-1, but not HIV-2 and Rous-associated virus 2 (RVA-2) RT. Conversely, HIV-2 RTI antibody specifically inhibited HIV-2 RT, but not HIV-1 and RAV-2 RT. These findings agreed with previously reported results showing the type-specificity of HIV-1 and -2 RTI antibodies, and suggest the possibility that isolated retroviruses could be identified by these antibodies.

Biotin↗
PubMed1993

Inhibition of myosin light chain phosphatase during Ca(2+)-independent vasocontraction.

Phorbol 12,13-dibutyrate (PDB) induced a sustained contraction of rat thoracic aorta strip in Ca(2+)-free buffer without significant change in intracellular free Ca2+ concentration. NKH477, a water-soluble forskolin derivative, markedly relaxed the PDB-induced contraction. The PDB-induced contraction was associated with the phosphorylation of 20-kDa myosin light chain (MLC). Two-dimensional phosphopeptide mapping of 20-kDa MLC revealed that approximately 90% of the phosphopeptides was derived from an MLC kinase-catalyzed reaction and approximately 10% was due to phosphorylation by protein kinase C. NKH477 inhibited the PDB-induced phosphorylation of 20-kDa MLC. MLC phosphatase activity of intact aorta strips was inhibited by the treatment with PDB, and the inhibition was recovered by the application of NKH477. These results suggest that the regulation of MLC phosphatase in vascular smooth muscle may play important roles in the PDB-induced contraction and the NKH477-induced relaxation in Ca(2+)-free buffer.

Animals↗
PubMed1993

Relation of phasic coronary flow velocity profile to clinical and hemodynamic characteristics of patients with aortic valve disease.

BACKGROUND: Our objective was to assess phasic coronary blood flow and velocity characteristics of the proximal portion of the left anterior descending artery and to evaluate their relation to the clinical and hemodynamic manifestations in patients with aortic valve disease. METHODS AND RESULTS: We examined 26 patients with chronic aortic regurgitation (AR), 12 patients with predominant aortic stenosis (AS), and 11 control subjects using an intravascular Doppler catheter with spectral analysis. Angiographic assessment of AR identified 10 patients with mild regurgitation and 16 with severe regurgitation. The resting systolic coronary flow velocity-time integral (VTI) was significantly higher and the diastolic VTI was slightly but significantly higher in patients with severe regurgitation than in those with mild regurgitation (11.8 +/- 4.2 vs 4.1 +/- 1.1 cm, P < .001; 18.5 +/- 5.8 vs 13.2 +/- 3.2 cm, P < .05) and control subjects (4.0 +/- 1.0 cm, P < .001 and 13.3 +/- 3.6 cm, P < .05), respectively. Patients with AS had a slightly lower resting systolic VTI (3.8 +/- 1.4 cm) and a higher diastolic VTI (14.6 +/- 3.7 cm) than control subjects. Resting coronary blood flow was greater in patients with aortic valve disease than in control subjects. There was a significant correlation between the ratio of the resting systolic to diastolic VTI (S/D ratio) and the ratio of the aortic systolic to diastolic pressure (r = .75, P < .001) in patients with AR. The S/D ratio was inversely correlated with left ventricular systolic pressure (r = -.92, P < .001) and positively correlated with the ratio of the aortic systolic to diastolic pressure (r = .68, P < .05) in patients with AS. CONCLUSIONS: Our results indicate that hemodynamic changes related to aortic valve disease contribute to alterations in the resting phasic coronary blood flow and velocity profiles observed in these patients.

Aortic Valve Insufficiency↗
PubMed1993

Prospect for an additional laboratory criterion for rheumatoid arthritis.

The aim of the study was to establish the benefit of an additional hypothetical laboratory criterion for rheumatoid arthritis (RA), comprising positivity for antikeratin antibody (AKA) and/or antiperinuclear factor (APF). The tests were applied to a series of 308 hospital patients with various recent-onset inflammatory joint diseases who were followed for 3 years. The performance of APF and AKA was compared with rheumatoid factor (RF). The most sensitive (.72) but the least specific (.86) test for RA was the latex test. The most specific (.96) but the least sensitive (.33) test was AKA. Waaler-Rose and APF were intermediate. AKA and/or APF positive patients had significantly more erosions than patients negative for these autoantibodies. Despite the impressive performance characteristics of APF and AKA, the actual classification impact achieved, as compared to using RF as the sole laboratory criterion, turned out to be moderate. This is because the criteria proved to be interrelated. Unlike RF, AKA and APF are not suited to the general laboratory, at least not in their present form. Moreover they so far lack the broad data base of RF.

Antibodies↗
PubMed1993

[Plasma coagulation and fibrinolysis parameters in patients with vascular Behçet's disease, and analysis of the multimeric structure of von Willebrand factor (vWF)].

We studied the relationship between vascular complications and coagulation and fibrinolysis parameters in ten subjects with Behçet's disease. We found that patients with Behçet's disease were in a state of hypercoagulation and hyperfibrinolysis. In vascular Behçet's disease in particular, coagulation and fibrinolysis parameters appeared to be indices of vascular complications. Analysis of the multimeric structure of von Willebrand factor (vWF) revealed a tendency for large multimer of vWF to increase in patients with Behçet's disease with accompanying vascular complications, whereas such increase were not observed in patients with Behçet's disease without any vascular complications. Therefore, analysis of vWF multimeric structure and the determination of coagulation and fibrinolysis parameters in plasma appear to be useful indicators of vascular complications in Behçet's disease.

Adolescent↗
PubMed1993

[A case report of acute mid-graft occlusion of the left internal mammary artery to the left anterior descending artery after PTCA].

A 66 year-old woman underwent coronary artery bypass grafting for postinfarction angina. A left internal mammary artery graft was joined to the left anterior descending artery. Coronary and graft angiography revealed a 90% stenosis in the anastomotic site of the left internal mammary artery. During PTCA with a 2.0 mm balloon catheter, acute occlusion of the graft body occurred. Intragraft injection of isosorbide dinitrate failed to dilate the graft. Thus, careful consideration should be given to several complications such as acute occlusion of the graft when PTCA for anastomotic site of the graft is performed.

Acute Disease↗
PubMed1992

Purification of factor XIa inhibitor from human platelets.

An inhibitor of activated factor XI (FXIa) in human platelets was recently identified as an amyloid beta-protein precursor (APP). We purified an FXIa inhibitor (XIaI) from the supernatant of activated human platelets, and assessed its inhibitor activity toward FXIa amidolytic activity. Approximately 90 micrograms of XIaI that cross-reacted with anti-APP antibody was obtained from two hundred units of platelet suspension by employing a six-step column chromatography procedure. The molecular weight of the purified XIaI was 94,000. The Ki value of XIaI to factor XIa was 526 +/- 120 pM, and the inhibition was enhanced by the addition of ZnCl2. The amino-terminal sequence of XIaI was L-E-V-P-T-D-G-N-A-, which is identical to that for the leucine (N18) to alanine (N26) sequence of APP751 and the amino-terminal sequence of protease nexin-2.

Amino Acid Sequence↗
PubMed1992

Mitogenic activity of (-)epigallocatechin gallate on B-cells and investigation of its structure-function relationship.

(-)Epigallocatechin gallate (EGCg), the main constituent of green tea, strongly enhanced the direct plaque-forming cell (PFC) response to sheep red blood cells (SRBC) in vitro and showed strong mitogenic activity for mouse splenic B-cells but not for splenic T-cells and thymocytes. The enhancement of B-cell proliferation was not mediated by macrophages since their removal did not eliminate the activity. Among the derivatives of catechin examined, (+)catechin (C); (-)epicatechin (EC); (-)-epigallocatechin (EGC); (-)epicatechin gallate (ECg); (-)epigallocatechin gallate (EGCg); and theaflavin digallate (TF3), only the derivatives with the galloyl group (ECg, EGCg, and TF3) displayed significant enhancement of the spontaneous proliferation of B-cells. Structural analogs of the catechin and galloyl groups were also examined in the system. Gallic acid and tannic acid induced some enhancement, but rutin, pyrogallol and caffeine did not. The results indicate that the galloyl group on EGCg was responsible for enhancement. However, the basic conformations of the catechins are also important, because ECg, EGCg, TF3, gallic acid, and tannic acid had quite different potencies to induce B-cell proliferation.

Adjuvants, Immunologic↗
PubMed1992

[Protective activity of tea and catechins against Bordetella pertussis].

We examined the bactericidal activity of tea and catechins against Bordetella pertussis. Green tea, black tea and coffee showed marked bactericidal activity at their concentrations in beverages, while pu-erh tea killed the bacteria in a moderate way. (-) Epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) showed also marked bactericidal activity. Green tea and black tea also effectively blocked the adhesion of B. pertussis to HeLa and CHO cells, whereas ECGg and TF3 could not. EGCg and TF3 markedly inactivated leuco-lymphocytosis promoting activity of pertussis toxin. Black tea showed slight but significant inactivation of the activity, whereas green tea showed no inactivation. These results suggest that green tea, black tea, EGCg and TF3 might act as prophylactic agents against pertussis infection.

Animals↗