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Biomedical subjects

A Hirata

Publications and source records attributed to A Hirata.

At least 199 records · Page 11Linked to original sources
PubMed1991

Brefeldin A blocks an early stage of protein transport in Candida albicans.

Brefeldin A (BFA) inhibited in a dose-dependent manner secretion of the cell-surface enzyme acid phosphatase (APase) into the periplasm of Candida albicans and caused intracellular accumulation of enzyme protein. Cells grown in the presence of BFA became more dense, implying that cell-surface growth was also blocked by BFA treatment. The APase that was accumulated intracellularly migrated faster on SDS-PAGE, suggesting less N-linked glycosylation compared with the mature, periplasmic APase produced in the absence of BFA. Pulse-chase experiments and gel-filtration of oligosaccharides released by Endo H treatment suggested that the core-glycosylated precursor form of APase accumulated in the presence of BFA. These results strongly suggested that endoplasmic reticulum (ER)-to-Golgi transport in C. albicans was inhibited by BFA. Aberrant membrane structures were observed in BFA-treated cells. Within 1 h of BFA removal these structures were replaced with rough ER membranes, suggesting that the accumulated membranes were derived from the ER.

Acid Phosphatase↗
PubMed1991

Cytochemical studies of transitional area between retina and optic nerve.

We have investigated the fine structural features of the transitional area between retina and optic nerve with special emphasis on the identification of Müller cells using the cytochemical method for detecting the localization of G6Pase activity, which is specific to the endoplasmic reticulum (ER) of Müller cells in the guinea pig retina. This cytochemical method enabled us to differentiate Müller cells from astrocytes or other cells easily and also allowed topographical, three dimensional analysis by high voltage electron microscopy because of the high contrast of the reaction products. Our study demonstrates that Müller cells are a major constitutional element of intermediary tissue of Kuhnt, which is considered to be the possible site of barrier between optic nerve and retina. These findings may indicate that Müller cells contribute to the barrier function in this region of the eye.

Animals↗
PubMed1991

Combined cytochemical detection of Müller-cell-specific enzyme activity and permeability tracers.

A combination of cytochemical methods in one tissue section was studied in order to detect the contribution of Müller cells to the blood-ocular barrier. Applications are shown for the detection of Müller cells and peroxidatic enzymes. The following advantages of the present method were demonstrated: superior sensitivity of glucose-6-phosphatase (G6Pase) activity, which allows the detection of these cells even in the coagulated retina. The reaction products showed no deleterious change after a subsequent reaction. These factors, and the contrasting reaction products of G6Pase and the enzymatic tracers (especially those of horseradish peroxidase) allow the distinction of Müller cells and the functional barrier site.

Animals↗
PubMed1991

[Eosinophil cationic protein in patients with bronchial asthma].

To evaluate the role of eosinophils in the pathogenesis of bronchial asthma, we measured eosinophil cationic protein (ECP), one of the eosinophil granule proteins. Serum ECP levels were measured by radioimmunoassay in asthmatic (n = 59) and non-asthmatic (n = 47) patients. Preliminary study showed that ECP levels were time-dependently increased in the blood samples until 3 hr. Based on the findings, we determined to measure serum ECP levels at 30 min after blood sampling. Serum ECP levels and blood eosinophil counts in asthmatic patients were significantly higher than those in non-asthmatic patients (p less than 0.01). There was also a positive correlation between serum ECP levels and blood eosinophil counts in patients with asthma (r = 0.46, p less than 0.001). No significant difference was observed in either serum ECP levels or blood eosinophil counts in asthmatic patients classified by clinical type and severity. Blood eosinophil counts in patients with asthma attacks were significantly greater than in those in remission (p less than 0.05), but no significant difference was observed in serum ECP levels between these groups, suggesting an enhanced elimination of ECP during attack. Serum alpha-2 macroglobulins, which bind to ECP and may function as scavengers for ECP, were not significantly different in these group. These results suggest that serum ECP levels may not be a direct indicator of eosinophil activation or degranulation in the pathogenesis of asthma.

Adult↗
PubMed1991

Integral photodynamic therapy of superficial bladder tumors with special reference to carcinoma in situ.

Whole bladder wall photodynamic therapy using hematoporphyrin derivative and argon-dye laser light 630 nm was performed on 40 patients with mainly carcinoma in situ of the bladder. Two types of laser light scattering diffuser developed at our department were used: motor-driven and endoscope-modified laser light scattering diffusers. The total energy density used was 10 to 30 Joules/cm2. Of the 40 patients, 27 (67.5%) achieved complete response and 5 (12.5%) partial response at 3-months follow-up. In 11 of the 27 patients, there was no recurrence with an average tumor-free time of 26.3+/-26.1 months ranging from 3 to 75 months. Bladder capacity was reduced to approximately 150 ml for 3 months after treatment without any evidence of hydronephrosis or excretory urograms, except for 2 patients who had contracted bladders before treatment. The suitability of sulphonated AlCl phthalocyanine, a new photosensitizer to replace HpD, is discussed.

Adult↗
PubMed1990

Purification of inactivated photoresponsive nitrile hydratase.

Photoresponsive nitrile hydratase from Rhodococcus sp. N-771 was purified in its inactivated form. The enzyme had a molecular weight of approximately 60 kDa and consisted of 2 subunits each having molecular weight of 27.5 and 28 kDa. The enzyme also contained 2 iron atoms/enzyme as a cofactor. The enzyme was more stable in its inactivated form, rather than the activated during storage in the dark. The enzyme was most stable in the temperature region of 0-35 degrees C, and lost its activity above 40 degrees C. The enzyme was most stable in the pH region of 6-8. The optimum temperature and pH for the enzyme activity was 30 degrees C and 7.8, respectively. The enzyme showed wide substrate specificity, and most of the metal ions did not affect enzyme activity significantly. The absorption spectrum revealed the presence of some cofactor which changed form after photoirradiation.

Enzyme Activation↗
PubMed1990

Effects of synthetic estrogens, (R,R)-(+)-, (S,S)-(-)-, dl- and meso-hexestrol stereoisomers on microtubule assembly.

We previously reported on the inhibition of microtubule polymerization and the formation of ribbon structures by synthetic estrogens [Sato et al., J Biochem 101: 1247-1252, 1987]. The present investigation aimed to analyse these effects in vitro on stereochemical point of view, using hexestrol isomers ((R,R)-(+)-hexestrol, (S,S)-(-)-hexestrol and meso-hexestrol) and dl-hexestrol. Among hexestrols, dl-hexestrol showed the highest activity in ribbon formation from microtubule proteins at 100 microM. On the other hand, meso-hexestrol was distinguished from others by inhibition of microtubule assembly and formation of a large amount of aggregates from purified tubulin in the presence of MgCl2 and DMSO. These results were discussed with physico-chemical properties of hexestrols, e.g. absolute configurations as well as circular dichroism spectra and solid state carbon-13 nuclear magnetic resonance spectra.

Animals↗
PubMed1990

Biology of phospholipase inhibitory proteins.

Our present results showed that calpactins might be not the proteins whose synthesis is modulated by glucocorticoids, and suggest that there may be another type of PLA2 inhibitory protein which directly interact with PLA2 and whose synthesis is induced by glucocorticoids. Further characterization and isolation of this protein will provide the most concrete evidence in this aspect.

Animals↗
PubMed1990

Effect of hypoxia on electrical activity of atrioventricular nodal cells and atrial cells of the rabbit's heart.

The effect of hypoxia on the electrical activities of atrial cells and atrioventricular (AV) nodal cells (AN, N, NH) excised from the rabbit heart were examined. Within 5 minutes under a hypoxic condition, N cells and NH cells of the AV node responded in a 2:1 manner to electrical stimulation with a basic cycle length of 300 msec, but atrial cells and AN cells of the AV node responded in a 1:1 manner. Even after 120 minutes of hypoxia, atrial cells and AV nodal cells responded in a second-degree fashion to electrical stimulation with a basic cycle length of 300 msec. After 10 minutes, 60 minutes, and 120 minutes of hypoxia, shortest pacing basic cycle lengths with 1:1 responses to electrical stimulation increased significantly. AV nodal automaticity rate decreased significantly. AV nodal automaticity rate decreased significantly after 10 minutes and 120 minutes of hypoxia. After 120 minutes of hypoxia, reoxygenation for 30 minutes produced complete recovery of action potential characteristics in atrial cells but not in AV nodal cells.

Action Potentials↗
PubMed1990

Immunopharmacological study of sulfated schizophyllan (SPG). I.--Its action as a mitogen and anti-HIV agent.

Sulfated schizophyllans of differing sulfur content were prepared and their mitogenic activities and effects on human immunodeficiency virus (HIV) were investigated in vitro. The sulfated schizophyllans were found to possess mitogenic activity. Anti-viral activity was evaluated in terms of cytopathic effect, and by the fluorescence antibody technique, reverse transcriptase assay and cell proliferation assay. Schizophyllans with a higher sulfur content showed potent anti-HIV effects on Molt-4 clone No. 8 or MT-4 cells infected with HIV as well as on lymphocytes from AIDS patients. It is suggested that the sulfur content of schizophyllans is the most important factor for inhibiting growth of HIV, rather than molecular weight or kinds of sugar component. Thus, sulfated schizophyllans appear applicable as anti-HIV drugs.

Acquired Immunodeficiency Syndrome↗
PubMed1990

The functional domain of adenylate cyclase associated with entry into meiosis in Saccharomyces cerevisiae.

Diploid yeast cells that carry a part of the CYR1 gene deficient in a region coding for the N-terminal domain of adenylate cyclase were growth arrested and accumulated unbudded cells after inoculation into complete medium or nitrogen-free medium, but produced many cells which had one or more buds after incubation in sporulation medium. The cells incubated in sporulation medium had abnormal spindles which were free from the spindle pole bodies, larger in size, or frequently distributed in cytoplasm. The levels of cyclic AMP in these cells did not decrease to the wild-type level after transfer to the sporulation medium and remained at a constant level. The results suggest that the N-terminal domain of adenylate cyclase is associated with the regulatory function for sporulation. The environmental signals for sporulation may be transferred to the adenylate cyclase system through a factor that negatively interacts with the N-terminal domain of this enzyme.

Adenylyl Cyclases↗
PubMed1990

Effect of meso-hexestrol, a synthetic estrogen, on S-tubulin.

We have reported that meso-hexestrol, a synthetic estrogen, inhibits microtubule assembly and induces microtubule proteins into twisted ribbon structures. On the other hand, Serrano et al. proved that S-tubulin, which lacks the C-terminal moiety of tubulin subunits, assembles into sheet structures in the absence of microtubule-associated proteins (MAPs). In the present investigation, we attempted to clarify whether meso-hexestrol could induce the ribbon structure from S-tubulin. meso-Hexestrol delayed the initiation of polymerization of S-tubulin into sheet structures in a dose-dependent manner below 50 microM. But the effect of meso-hexestrol on S-tubulin was reduced in the presence of either tau or microtubule-associated protein 2 (MAP2) in a MAPs-concentration-dependent manner. At concentrations higher than 100 microM, meso-hexestrol inhibited the polymerization of S-tubulin into sheet structures, without forming ribbon structures. The present results may indicate that moso-hexestrol interacts with S-tubulin, and its interaction is affected by MAPs.

Animals↗
PubMed1990

Resorthiomycin, a novel antitumor antibiotic. I. Taxonomy, isolation and biological activity.

Resorthiomycin, a novel antitumor antibiotic, was isolated from the fermentation broth of a strain of Streptomyces collinus by ethyl acetate extraction, silica gel chromatography and HPLC. Resorthiomycin exhibited an in vitro cytotoxic activity against mouse leukemia L5178Y cells (IC50, 15.5 micrograms/ml) and also inhibited the clonogenic activity of a multidrug-resistant mutant of human hepatoma PLC/PRF/5 cells to a greater extent than that of the parental cells. On the other hand, this antibiotic does not possess any antibacterial or antifungal activity.

Animals↗
PubMed1990

Preparation of polyclonal antibodies to an anti-tumor (1----3)-beta-D-glucan, schizophyllan.

Antibodies against Schizophyllan (SPG) or SPG conjugated with bovine serum albumin (BSA) were raised in rabbits by multiple subcutaneous immunization. The titer of SPG-reactive antibodies in the antiserum to SPG-BSA conjugate was significantly higher than in the antiserum to SPG as assessed by enzyme-linked immunosorbent assay (ELISA). The SPG-reactive antibodies purified by affinity chromatography using a Protein A-Sepharose CL-4B column interacted with the SPG-BSA conjugate spotted on a nitrocellulose membrane filter in a dose-dependent manner, but the anti-SPG antibodies did not interact with BSA. Immunocytochemical staining has also shown that the anti-SPG antibodies reacted with SPG taken up by mouse peritoneal macrophages.

Animals↗
PubMed1990

[Relapsed stage I neuroblastoma successfully treated by allogeneic bone marrow transplantation in second remission: case report of a 7-year-old girl].

Stage I neuroblastoma in a seven-year-girl have had local recurrence with bone metastasis. Second surgery was performed after the aggressive chemotherapy including cisplatin, VP16, cyclophosphamide, vincristine and doxorubicin. She underwent allogeneic bone marrow transplantation from her HLA identical brother, following the preparative regimen consisting of high-dose melphalan and total body irradiation (12 Gy). Clinical course after the transplantation was uneventful. She is still alive with no evidence of disease for twenty-eight months after the transplantation. It is suggested that bone marrow transplantation is an effective way of therapy even in a patient with relapsed neuroblastoma.

Adrenal Gland Neoplasms↗
PubMed1990

[Phthalocyanine: a new photosensitizer in photodynamic therapy].

Photodynamic therapy (PDT) with hematoporphyrin derivative (HpD) combined with laser irradiation has been introduced as a new promising clinical method for the treatment of various malignancies. Recently, sulphonated aluminum chloro phthalocyanine (A1PC) has attracted a great deal of attention as a new photosensitizer. Tissue concentrations and photodynamic effects of A1PC and HpD, that has been using clinically in PDT, were determined in nude mice transplanted bladder tumors. According to the tissue distribution of A1PC and HpD at various times after administration, the ratios of tumoral concentration to muscular concentration of A1PC were higher than those of HpD, and skin concentration of A1PC at 24 to 168 hrs. after administration was lower than that of HpD. These results suggest that more A1PC localizes in malignant tumor than HpD, and there is a possibility of reducing skin photosensitivity with A1PC as compared with HpD. The regression of tumor volume after PDT was higher with A1PC and laser light at 670 nm than with HpD and laser light at 630 nm.

Animals↗
PubMed1989

[Clinical evaluation for voiding dysfunction in patients with cerebral-palsy].

Urological assessments were done on 132 patients with cerebral palsy, ranging from 5 to 59 years in age (mean 23.2). Concerning urological symptoms, urinary incontinence, decreased urinary stream and urinary tract infection were at 31.8, 14.4 and 16.7%, respectively. Patients with functionally impaired ambulation had a high incidence of urinary incontinence and decreased urinary stream. Decreased urinary stream was more prominent in an elderly patient group, and urinary incontinence was observed almost at the same rate in all age-classified groups. Urodynamic studies were performed in 30 patients with cerebral palsy who were referred to with urological symptoms. The patients were classified into two groups according to the presence or absence of spinal cord lesions. In a group of 15 patients with spinal cord lesions, electromyography of the external sphincter demonstrated detrusor-sphincter dyssynergia (DSD) in 9, of whom 6 complained of decreased urinary stream; while in the group without spinal cord lesions there was no DSD. These findings suggest that the cause of decreased urinary stream in cerebral palsied patients could be explained by DSD secondary to spinal cord lesions.

Adolescent↗