Biomedical subjects

M Okabe

Publications and source records attributed to M Okabe.

At least 397 records · Page 22Linked to original sources

PubMed1986

Inconsistent reactivity of an anti-sperm monoclonal antibody and its relationship to sperm capacitation.

An anti-sperm monoclonal antibody was developed from female C57BL/6 mice immunized with epididymal sperm from a syngeneic male mouse. Immunofluorescence staining revealed that the antibody did not react to fresh epididymal sperm but attached to the capacitated sperm found in the peri-vitelline spaces of the ova. When the antibody was applied to sperm incubated in vitro, variously stained sperm were observed. It was presumed that the antigenic site detected by the antibody was hidden in the fresh epididymal sperm and was spread from the acrosomal cap region to the entire head during the capacitation process.

Animals↗

PubMed1986

Chromophore/protein interaction in bacterial sensory rhodopsin and bacteriorhodopsin.

Retinal analogues with altered conjugated double bond systems or altered stereochemistry were incorporated into the phototaxis receptor sensory rhodopsin (SR) and the light-driven proton pump bacteriorhodopsin (BR) from Halobacterium halobium. Wavelength shifts in absorption ("opsin shifts") due to analogue interaction with the protein microenvironment demonstrate that the same overall electrostatic and steric properties of the retinal binding-site structures exist in both proteins despite their different functions. pi-Electron calculations from the opsin shifts lead to a new description of protein charge distribution that applies to the binding sites of both SR and BR. The new data extends the previously proposed external point charge model for BR to include an ion-pair protein/chromophore interaction near the beta-ionone moiety. The new data modifies the previously proposed external point-charge model, the derivation of which involved an experimentally erroneous opsin shift for one of the BR analogues.

Bacteriorhodopsins↗

PubMed1986

Impaired alpha-interferon production and natural killer activity in blood mononuclear cells in myelodysplastic syndromes.

The producibility of interferon (IFN)-alpha, which indicates one of the functions of large granular lymphocytes (LGL), was impaired at a high frequency in myelodysplastic syndrome (MDS) patients. However, IFN-alpha production in refractory anaemia, which is a subtype of MDS, was almost normal. In contrast, abnormality has not been observed in either proliferative response or the production of IFN-gamma of T-cells by stimulation with PHA. NK activity of peripheral blood mononuclear cells (PBMC) from MDS patients was generally low and was not augmented by IFN-alpha treatment. These results indicate that, in addition to the abnormality at the level of haematopoietic tissues, LGL among PBMC may be impaired in MDS patients.

Adult↗

PubMed1986

Potent platelet antiaggregant action of an antiarrhythmic peptide (AAP).

A potent platelet antiaggregant action of an antiarrhythmic peptide (AAP) was demonstrated to be a cause of the antithrombotic effect. AAP (10, 20 or 40 mg/kg, i.v.) inhibited ex vivo platelet aggregation induced by collagen in a dose-dependent manner. AAP also inhibited the platelet aggregation of platelet-rich plasma (PRP) induced by collagen, Ca-ionophore A-23187, adenosine diphosphate (ADP), thrombin or arachidonic acid in vitro. The IC50 was 2.5 mM for collagen, 1.7 mM for A-23187, 5 mM for ADP, 0.4 mM for thrombin and 0.15 mM for arachidonic acid. The aggregation inhibitory activity of the peptide on washed platelet (WP), in a Ca2+-free medium, was stronger than on PRP. The IC50 was 1 mM for collagen and 20 microM for A-23187. No significant difference was found between antiaggregant activities of platelet-free plasma (PFP) from AAP-treated rats and PFP from normal rats supplemented with AAP. The direct action of AAP on platelets was also supported by the incorporation of AAP into platelet cytoplasma which caused a decrease of Ca2+-dependent 3':5'-cyclic nucleotide phosphodiesterase (Ca-PDE) activity. It was considered that AAP showed its platelet aggregation inhibitory activity by decreasing intracellular Ca2+ concentration through the inhibition of Ca-PDE activity.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1986

Studies on pharmacological activation of human serum immunoglobulin G by chemical modification and active subfragments. IV. Induction of anti-inflammatory activity by chemical cleavage of interchain disulfide bonds in human immunoglobulin G and pharmacological activity of alkylated subfragments.

Commercially available human serum immunoglobulin G (IgG, native IgG) was separated into two fractions (Fr.I and II) using a diethylaminoethyl cellulose column. Heavy and light chains containing fractions were obtained from these two fractions after carboxamide-methylation. Thus, these fractions were subjected to an anti-inflammatory screening procedure and were shown to have a potent inhibitory activity against rat carrageenin induced paw edema, while no effect was observed in native IgG, Fr.I or II. The reduction and alkylation of the interchain disulfide bonds were essential to induce the anti-inflammatory activity. The anti-inflammatory activity of alkylated heavy and light chains of Fr.I (Fr.I-H and I-L) was also noted in subacute inflammation caused by the felt pellet and croton oil granuloma methods. Moreover, strong membrane stabilizing activities of Fr.I-H and I-L were demonstrated in vitro using rat red blood cell membrane and liver lysosomal membrane.

Alkylation↗

PubMed1986

Studies on sperm capacitation using monoclonal anti-body--disappearance of an antigen from the anterior part of mouse sperm head.

C57BL/6 mice were immunized with cauda epididymal sperm from syngenic mice. A monoclonal antibody (TSC4) was obtained using a hybridization method with myeloma (P3U1) cells. The antibody was examined for its reactivity to sperm from different regions of the reproductive tract of male mice. The antigen was recognized only when the sperm reached the corpus epididymis. The area of antigen present on the sperm membrane was topographically restricted to the anterior part of sperm head. The antigen remained on the sperm after washing with phosphate buffered saline, disappearing, however, when sperm was capacitated.

Animals↗

PubMed1986

Studies on pharmacological activation of human serum IgG by chemical modification and active subfragments. V. Mechanism of anti-inflammatory action of carboxamide-methylated L-chain (Fr. I-L) and H-chain (Fr. I-H) from human serum IgG.

Using the xylene ear method in mice, it was demonstrated that the reduced and carboxamide-methylated fragments of human serum IgG (Fr. I-H and Fr. I-L) significantly suppressed capillary permeability. It was also shown that leucocyte emigration and protein leakage into and esterase activity of the pouch fluid, which was accumulated by carboxy-methyl cellulose injections, were suppressed by the administration of the fragments. Moreover, the lipid peroxide level was lowered by both Fr. I-H and Fr. I-L in the liver of either carrageenin-induced, paw edema-bearing or kaolin pouch inflammation in rats. The facts obtained in this study indicated the mechanisms of the anti-inflammatory effects of Fr. I-H and Fr. I-L were mainly caused by both the inhibitory effect on leucocyte emigration into the site of injury and stabilization of the membrane by inhibiting lipid peroxidation of the inflammatory tissue.

Acid Phosphatase↗

PubMed1986

Response of immunoreactive antiarrhythmic peptide (IR-AAP) level associated with experimental arrhythmia in rats.

The change in endogenous antiarrhythmic peptide (AAP) levels in serum, heart and kidney from rats under several drug-induced arrhythmias was investigated using a sensitive and specific radioimmunoassay. The extracts from serum, heart and kidney were fractionated by Sephadex G-25 chromatography to obtain a fraction which was found at the same position as that of synthetic AAP. In serum, the immunoreactive (IR)-AAP level increased about threefold under CaCl2-, aconitine- and epinephrine-induced arrhythmias. In heart, the IR-AAP level was doubled by CaCl2, increased 1.4 times by aconitine and decreased by one third by epinephrine. The levels in serum and heart were slightly increased by ADP. The kidney IR-AAP level was not changed under these drug-induced arrhythmias. Considering the previous result that AAP could protect against CaCl2- and aconitine-induced arrhythmias but not against epinephrine-induced arrhythmia, the change in the IR-AAP level in heart coincided with the effect of AAP given to animals under arrhythmia. Quinidine, propranolol and verapamil had no effect on serum IR-AAP level. These results suggested that endogenous AAP in heart worked to suppress certain arrhythmia.

Aconitine↗

PubMed1986

Synergistic anticellular and antiviral activities of human recombinant interferon-gamma and -beta.

The synergism of anticellular and antiviral activities of recombinant human interferon-gamma (ReIFN-gamma) and recombinant human interferon-beta (ReIFN-beta) was examined in vitro using human melanoma SK-MEL-28 cells. Some differences were detected in the kinetics of anticellular activity between both IFNs, namely the inhibitory effect of ReIFN-beta occurred earlier than that of ReIFN-gamma. Significant synergism was detected in the anticellular activity of both IFNs when growth curves and isobolograms were examined. A difference between ReIFN-gamma and ReIFN-beta was also detected in antiviral activity. The antiviral activity of ReIFN-gamma against vesicular stomatitis virus (VSV) was significantly weaker than that of ReIFN-beta, even though both IFNs exhibited almost equivalent antiviral activities against Sindbis virus. However, ReIFN-gamma and ReIFN-beta exhibited synergistic antiviral activities against both VSV and Sindbis virus. The analysis of cell cycle distribution by flow cytometry revealed that there were some differences in the distribution pattern between cells treated with ReIFN-gamma alone, ReIFN-beta alone, or ReIFN-gamma and ReIFN-beta in combination. ReIFN-beta induced a prolongation or accumulation of S phase, whereas the effect of ReIFN-gamma was cycle-nonspecific. The combination of ReIFN-gamma and ReIFN-beta induced a decrease of G1 phase and an increase of G2M phase. These results suggest that ReIFN-gamma and ReIFN-beta used in combination were more effective in inhibiting the growth of human tumor cells and the proliferation of viruses than IFN used individually.

Antineoplastic Agents↗

PubMed1986