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Biomedical subjects

K Okubo

Publications and source records attributed to K Okubo.

At least 271 records · Page 15Linked to original sources
PubMed1991

Composition and structure of "group B saponin" in soybean seed.

The composition of "group B saponin" in soybean seed was analyzed by HPLC, and six kinds of "group B saponin," named Ba, Bb, Bb', Bc, Bd and Be according to elution order from HPLC, were detected. Of these saponins, Ba, Bb, Bb' and Bc were identified with soyasaponin V, I, III and II, respectively. Bd and Be were novel saponins possessing soyasapogenol E as the aglycone and the same sugar chain as Ba and Bb, respectively. These saponins were very unstable in the isolated state and had a tendency to form Ba and Bb, respectively. From these results, Bd and Be are presumed to be the precursors of Ba and Bb in soybean seed.

Chromatography, High Pressure Liquid↗
PubMed1990

[A case report of hemolytic uremic syndrome (HUS) induced by antineoplastic agents].

An autopsy case of hemolytic uremic syndrome after treatment with antineoplastic agents for advanced gastric carcinoma is reported. A 70 year-old woman underwent partial gastrectomy for gastric carcinoma on April 16, 1987 (P0H0S2N4, Stage IV). She was treated with Mitomycin C (MMC), UFT, OK-432 and PSK as post operative chemotherapy. Total doses were 60 mg of MMC, 33.9 g of UFT, 55 KE of OK-432 and (507 g) of PSK. She suffered from occult blood in urine in September 1987, thrombocytopenia and anemia in October, edema and hypertension in November and died due to acute renal failure and pulmonary failure on December 5, 1987. It seemed that the cause of death was hemolytic uremic syndrome induced by antineoplastic agents.

Aged↗
PubMed1990

Alterations in membrane fluidity during keratinocyte differentiation measured by fluorescence polarization.

The epidermis shows a distinctive pattern of differentiation wherein keratinocytes proliferate in the basal cell layer and mature into spinous and granular cells. Using a discontinuous density-gradient centrifugation method, guinea-pig keratinocytes were separated into high (HDF), intermediate (IDF), and low (LDF) density fractions. Morphological and flow cytometrical observations demonstrated that HDF, IDF, and LDF were basal, spinous, and granular cell-rich fractions, respectively. Membrane fluidity of the fractionated keratinocytes was measured by diphenylhexatriene fluorescence polarization. Polarization (p)-value of keratinocytes was negatively correlated with temperature. At each temperature, HDF cells showed a lower p-value than IDF or HDF cells except at 40 degrees C. Since a low p-value indicates a high degree of Brownian motion, membrane fluidity is higher in basal cells and lower in spinous and granular cells. Our results indicate that membrane fluidity of guinea-pig keratinocytes decreases during their maturation.

Animals↗
PubMed1990

Inhibition of chloride binding to the anion transport site by diethylpyrocarbonate modification of Band 3.

The line widths of 35Cl- nuclear magnetic resonances were used to measure chloride binding by Band 3. Since this procedure relates directly to binding, the data obtained may be interpreted more unequivocally than affinities derived from kinetic data which could be related to either translocation or binding. Chloride binding to the active sites in Band 3 was assessed from that portion of the total line width which was sensitive to 4,4'-dinitrostilbene-2,2'-disulfonic acid. These sites appeared to be completely inhibited by treatment of erythrocyte membranes with diethylpyrocarbonate. This result is consistent with our previous observation that this reagent inhibits anion transport in resealed erythrocyte ghosts (Izuhara, Okubo & Hamasaki, 1989, Biochemistry 28:4725-4728). Hydroxylamine could not reverse the diethylpyrocarbonate inhibition of chloride binding to Band 3. The pH-dependence of diethylpyrocarbonate reactivity suggests that the modified residues may be those of histidine.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1990

Different type of hepatitis B virus (HBV) DNA integrants that may reflect the integration process.

Through analyses of HBV DNA integratns in human cellular DNA, we identified three different integrant types, each of which may reflect the process of primary integrant formation by the viral DNA. The first type, which we call "simple type" consists of integrants found in some hepatocellular carcinomas (HCC's). The structure of the viral genome is simple, and part of it is deleted. The viral cohesive end sequence appears at one of the viral-cellular DNA junctions, and integration has elicited a microdeletion in the target cellular DNA sequence. This structure suggests viral DNA replication intermediates as substrates for integration. Judging from its frequency in HCC, this type may represent the most preferred one, if not all, among the primary integration products. The second type, which we call "complex type" is essentially the same as the first type, except tht the viral genome structure is complex. We considered the possibility that they may have been produced via the same process, using preformed complex viral genomes such as "novel form DNA's" (Rogler and Summers, 1982) as substrates. In cultured fetal hepatocytes, integration of HBV DNA can occur only a few days after infection. Among such integrants, we found a third type integrant, having a simple viral genome, but having a larger cellular DNA deletion. We propose that different forms of viral DNA may be used as substrates in the integration process, and the process is characterized by its eliciting of deletions of different size in the target cellular DNA. The most preferred substrate may be the one producing the simple type integrants, and the most frequently occurring deletion in the target DNA may be the microdeletion.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1990

[Autoregulation of macular capillary blood flow evaluated by the blue field entoptic phenomenon].

Autoregulation of the macular capillary blood flow was investigated using a blue-field entoptoscope and OCVM suction cup system. The perfusion pressure was reduced by elevation of the intraocular pressure with a Langham's suction cup placed on the temporal sclera. The results showed that the autoregulatory response maintains the macular capillary blood flow velocity until the perfusion pressure is reduced to approximately 25 mmHg. The Closed-loop gain of the autoregulatory response functions at a perfusion pressure as low as approximately 10 mmHg, below which it did not work well.

Adult↗
PubMed1990

[Two cases of idiopathic preretinal macular fibrosis in children].

We report herein the findings in two patients less than 15 years old with the diagnosis of idiopathic preretinal macular fibrosis, a disorder found primarily in the older population. Only a few reports have discussed idiopathic preretinal macular fibrosis in children and its pathogenesis is still unknown. One is a 10-year-old boy and the other is a 14-year-old girl who visited our hospital with a chief complaint of blurred vision in their right eyes. Epiretinal membranes were recognized on the macular region of their right eyes. Since there was no causative factors, a diagnosis of idiopathic preretinal macular fibrosis was made. They were conservatively followed up. The vision of the boy once worsened but improved spontaneously and remained stable for three years. Because the vision of the girl worsened rapidly, vitreous surgery was performed to remove the epiretinal membrane, resulting in poor vision. It was suggested that this disorder in children should be followed up conservatively and the indication of vitreous surgery should be carefully determined.

Adolescent↗
PubMed1989

Conformational change of band 3 protein induced by diethyl pyrocarbonate modification in human erythrocyte ghosts.

Diethyl pyrocarbonate inhibited the phosphate exchange across the human erythrocyte membrane. The exchange rate was inhibited only when the membranes were modified with the reagent from the cytosolic surface of resealed ghosts. The intracellular modification by diethyl pyrocarbonate inhibited the extracellular binding of [3H]dihydro-4,4'-diisothiocyanostilbene-2,2'-disulfonic acid to band 3 protein. Furthermore, the extracellular 4,4'-dinitrostilbene-2,2'-disulfonic acid protected the membranes from the intracellular modification by diethyl pyrocarbonate. These results suggest that the extracellular binding of 4,4'-dinitrostilbene-2,2'-disulfonic acid to band 3 protein induces the conformational change of the intracellular counterpart of band 3 protein and the diethyl pyrocarbonate susceptible residue(s) is (are) hidden from the cytosolic surface of the cell membrane in connection with the conformational change. Conversely, under the conditions where the diethyl pyrocarbonate modification is confined to the intracellular side of the membrane, the extracellular binding site of [3H]dihydro-4,4'-diisothiocyanostilbene-2,2'-disulfonic acid is hidden from the cell surface.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1989

An in vitro system for infection with hepatitis B virus that uses primary human fetal hepatocytes.

An in vitro culture of human fetal hepatocytes has been employed for infection by hepatitis B virus (HBV) virions that are produced by an established human hepatoma cell line, HB 611. HBV surface antigen and e antigen were released into the medium 3-4 days after infection, and production continued thereafter. RNA synthesis with similar kinetics was observed. Viral DNA replication started 2 days after infection, and replicative HBV DNA that included relaxed circles, single-stranded minus strands, and closed circles accumulated during 16 days of incubation. Immunofluorescent study using fluorescein isothiocyanate-labeled rabbit antisera directed against HBV core antigen revealed that this antigen is present in the nuclei in 12% of the infected cells. Particles containing HBV DNA were detected in the culture medium and were infectious. Thus, this in vitro infection system closely mimics infection in vivo and it allows detailed studies on early events associated with human HBV entry into cells and subsequent replication and integration.

Carcinoma, Hepatocellular↗
PubMed1989

Inhibitory effect of glycosides like saponin from soybean on the infectivity of HIV in vitro.

Soybean saponins isolated from soybean seeds were investigated for their antiviral activity on HIV in vitro, using an HTLV-I-carrying cell line, MT-4. Saponin B1 completely inhibited HIV-induced cytopathic effects and virus-specific antigen expression 6 days after infection at concentrations greater than 0.5 mg/ml. Saponin B2 also inhibited HIV infection, although less potently. Both saponin B1 and B2 had no direct effect on the reverse transcriptase activity of HIV. Saponin B1 also inhibited HIV-induced cell fusion in the MOLT-4 cell system. The results of this study suggest that soybean saponins, especially saponin B1, have inhibitory activity against HIV infection.

Antiviral Agents↗
PubMed1989

The existence of a platelet-activating factor (Paf-acether)-like substance in blister fluid derived from patients with bullous pemphigoid as demonstrated by human platelet aggregation techniques.

We investigated the presence of a platelet-activating factor-like substance in blister fluid obtained from patients with bullous pemphigoid. Human platelet aggregation activity was present in blister fluids obtained from 4 out of 6 patients with bullous pemphigoid and in blister fluids obtained from 3 cases with contact dermatitis. Platelet aggregation activity of pemphigoid blister fluids was inhibited by pretreatment with lyso-PAF, which is a precursor metabolite of platelet activating factor. The activity of blister fluids obtained from patients suffering from contact dermatitis was not inhibited by precursor. Blister fluid obtained from burn lesions and blisters of normal skin induced in the suction revealed no platelet aggregation activity. These results suggest that platelet-activating factor or a similar substance is present in the blister fluid obtained from suffered bullous pemphigoid.

Adult↗
PubMed1989

[Analysis of the retinal blood flow by means of the blue field entoptic phenomenon and simulation of entoptic leucocytes with a personal-computer system].

A method was developed for determining the velocity of macular blood flow. Leukocytes flowing in the macular capillaries can be recognized when the retina is illuminated with blue light (blue field entoptic phenomenon). The motion of the leukocytes was simulated by a personal-computer system. The velocity of the macular blood flow was determined by adjusting the motion of the simulated corpuscles to that of the entoptically recognized leukocytes. The velocity of the maximum, minimum and mean macular blood flow were measured as 1.25 +/- 0.25, 0.42 +/- 0.11 and 0.80 +/- 0.14 mm/sec respectively. The mean coefficients of variation were 6.7%, 13.4% and 5.7% for each velocity. This method may be useful for the analysis of the retinal circulation and the diagnosis of retinal diseases.

Adult↗
PubMed1988

Localization of the pyridoxal phosphate binding site at the COOH-terminal region of erythrocyte band 3 protein.

A human erythrocyte Band 3 peptide, affinity labeled with pyridoxal phosphate, was purified by a combination of gel permeation and reverse-phase high performance liquid chromatography. The amino acid sequence of the transmembrane peptide was determined by sequencing subfragments of the peptide obtained from lysyl endopeptidase and staphylococcal proteinase V8 digestions. When a peptide containing the COOH-terminal of human erythrocyte Band 3 was also purified and sequenced, the affinity-labeled peptide was found to be located close to the COOH-terminal of Band 3, where it could be aligned with amino acid residues 852-927 of a murine erythrocyte Band 3, deduced from a nucleotide sequence of a cDNA clone (Kopito, R. R., and Lodish, H. F. (1985) Nature 316, 234-238). The amino acid sequence of the COOH-terminal region was highly homologous to that of murine Band 3. As a result, the sequence of the COOH-terminal peptide of Band 3 was established as follows. (Formula: see text). The pyridoxal phosphate binding site was identified as Lys-18 which corresponded to Lys-869 of the deduced sequence. It appears that the COOH-terminal region of Band 3 constitutes at least a part of the active center for anion transport in human erythrocyte membranes.

Amino Acid Sequence↗
PubMed1988

Purification of rat cutaneous mast cells with Percoll density centrifugation.

The skin is the major site on anaphylaxis, and cutaneous mast cells have an important role in its reactions. The isolation and purification of rat cutaneous mast cells are described here. Rat abdominal skin was digested with collagenase and hyaluronidase, and centrifuged with Percoll. The buoyant density of cutaneous mast cells was high, and relatively pure mast cells were obtained. The purity of cutaneous mast cells was 74% +/- 2.4% before and 50.0% +/- 6.4% after Percoll density centrifugation; peritoneal mast cells revealed 5.8% +/- 1.3% purity before and 61.0% +/-10.6% purity after the same procedure. The isolated cutaneous cells released 21.3% +/- 3.8% histamine and the peritoneal mast cells released 55.5% +/- 3.8% histamine upon stimulation with 10 micrograms/ml compound 48/80. These findings suggest that there are functional subsets of connective tissue mast cells.

Animals↗
PubMed1988

Effect of antianaphylactic agents on substance-P induced histamine release from rat peritoneal mast cells.

Substance P is known to be a potent histamine liberator for mast cells. The influence of antianaphylactic agents, disodium cromoglycate (DSCG), ketotifen, and tranilast was studied on substance-P and compound 48/80-induced histamine release from rat peritoneal mast cells. Substance-P induced histamine release was inhibited by these agents, while compound 48/80-induced histamine release was not inhibited by tranilast. Our findings suggest that these antianaphylactic agents are assumed to be effective for cutaneous diseases which might be concerned with substance P and histamine.

Animals↗
PubMed1987

[The factors necessary to achieve successful penetrating keratoplasty].

A statistical study was conducted of 31 penetrating keratoplasties performances over the past 6 years from January 1980 to December 1985, and the factors necessary to achieve successful penetrating keratoplasty are discussed on the basis of the results of the study. The patients were followed up for more than one year after operation. The graft transparency, visual acuity and incidence of corneal rejection were evaluated at one year after operation and the combined surgery with penetrating keratoplasty was also evaluated. The results obtained were as follows: 1) The distinctive feature of the cases with visual acuity of more than 1.0 were that the recipients were younger than 40 years of age and the donors were also less than 50 years at the time of the operation. 2) The patients with vascularized cornea showed a higher incidence of rejection and a lower successful ratio rate than did the avascular corneal patients. The above results indicate that the factors necessary to achieve a successful penetrating keratoplasty are young recipients, young donors and no vascularization of recipient cornea.

Adolescent↗