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Biomedical subjects

M Sakurai

Publications and source records attributed to M Sakurai.

At least 487 records · Page 27Linked to original sources
PubMed1992

Biosynthesis and n.m.r. studies of deuterated poly(3-hydroxybutyrate) produced by Alcaligenes eutrophus H16.

Alcaligenes eutrophus H16 was grown on mixtures of 1H- and 2H-acetate as carbon sources. The accumulation of deuterated poly(3-hydroxybutyrate) (P(3HB)) was observed. The deuterium distributions in the isolated P(3HB)s were determined from 1H and 2H-n.m.r. spectra and confirmed by 13C-n.m.r. spectra. Although one would expect to synthesize P([2,2,4,4,4-2H5]3HB) when the cells were grown on 2H-acetate as the sole carbon source, the methyl, methylene and methine groups of the P(3HB) contained both deuterium and proton. This observation indicates some substitution from 2H to 1H during the P(3HB) synthesis. The 2H content in the methyl groups was larger than that in the methylene groups, which suggests a kinetic isotope effect in the P(3HB) synthesizing process. The deuterium distributions in the two magnetically non-equivalent methylene protons were determined to be different, which indicates stereoselectivity at the C2 site.

Alcaligenes↗
PubMed1992

Recombinant human granulocyte colony-stimulating factor enhanced cytotoxicity of Ara-C in Ara-C-resistant leukemic cells from a patient with biphenotypic leukemia in cell kinetic quiescence.

In vitro preincubation with recombinant granulocyte colony-stimulating factor(rhG-CSF, 100 ng/ml) enhanced the cytotoxicity of 1-beta-D-arabinofuranosylcytosine(Ara-C) in leukemic cells resistant to Ara-C from a patient with biphenotypic leukemia. Treatment of the cells with rhG-CSF resulted in a 17-fold increase in DNA synthesis, 4.6-fold increase in percentage of S-phase, and a two-fold increase in Ara-CTP formation. Maximal effect was observed at 72 h of incubation. Combination chemotherapy with rhG-CSF and Ara-C to the patient showed remarkable cytoreduction. These results indicate that recruitment of resistant leukemic cells in cell kinetic quiescence is inducible by rhG-CSF and that it is possible enhancement of the cytotoxicity to cell cycle-specific drugs such as Ara-C.

Cell Cycle↗
PubMed1992

Flow cytometric analysis of effects of cytokines on the expression of varicella-zoster virus glycoproteins.

Varicella-zoster virus (VZV)-infected human embryonic fibroblast (HEF) cells were stained with monoclonal antibodies directed against VZV glycoprotein I, II and IV, and then labeled with fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse IgG. The cells were analyzed by flow cytometry. VZV-infected cells expressing VZV glycoproteins were clearly distinguished from uninfected cells. This method was useful for analyzing expression of VZV glycoproteins in different experimental conditions. Interferon alpha, beta, and gamma and tumor necrosis factor (TNF)-alpha reduced the percentage of positive cells and the mean fluorescence intensity of the cells expressing VZV glycoproteins. Interleukin(IL)-1 beta, IL-6 and TNF-beta had little effect on the expression of VZV glycoproteins.

Cells, Cultured↗
PubMed1992

Texture analysis of histological images of giant cell tumor of bone.

To gain an objective evaluation of histological sections of giant cell tumors of bone (GCT) and osteosarcomas, microscopic pictures were taken and their grey-tone image measured, using a flying spot scanner and computer. Various values of eight parameters expressing certain characteristical brightness distribution patterns were computed, and comparatively examined among the three groups of benign GCT, malignant GCT and osteosarcoma. As a result, some parameters could facilitate differentiation between the histological images of these bone tumors. Especially, "angular second moment (ASM)", "Contrast" and "Coefficient of variation (COV)" were useful even for discrimination between malignant and benign GCT. After factor analysis of the values of these parameters, scores of each factor for a number of histological scene images were plotted on a 2-dimensional factor plane. On this plane, which was considered to be a histological feature plane, cases of benign GCT were separated from those of osteosarcoma. Cases of malignant GCT were distributed between the two groups. These results suggest that this method could be valuable for computer evaluation of histological images of benign GCT and osteosarcomas.

Bone Neoplasms↗
PubMed1992

A world between realities: an exploration of therapeutic group culture and transitional phenomena in a long-term psychotherapy group.

In long-term, open-ended psychotherapy groups in which there are inevitable, yet potentially disruptive changes in membership, therapeutic group culture can become particularly important in sustaining a group's sense of cohesion. This article focuses on how transitional phenomena, as defined by D. W. Winnicott, and representational play serve as vehicles for establishing therapeutic group culture in a preadolescent girls' group. Applications of both transitional phenomena and therapeutic group culture to group stage development, as outlined by Garland, Jones, and Kolodny (1970), will also be explored.

Child↗
PubMed1992

Activation of lymphocytes by varicella-zoster virus (VZV): expression of interleukin-2 receptors on lymphocytes cultured with VZV antigen.

The expression of human leukocyte antigen (HLA-DR) and interleukin-2 receptor (IL-2R; alpha and beta subunits) was significantly increased in peripheral blood mononuclear cells (PBMC) from varicella-zoster virus (VZV)-seropositive donors when PBMC were cultured with VZV antigen for 6 days. The increased expression of HLA-DR and IL-2R was observed in both CD4+ and CD8+ lymphocytes, which suggests that both types of lymphocytes from VZV-seropositive donors were activated when PBMC were cultured with VZV antigen. Adding anti-IL-2R alpha did not inhibit lymphocyte proliferation in response to VZV antigen, although marked inhibition was obtained by adding anti-IL-2R beta. No IL-2 was detected in the supernatant of PBMC cultured with VZV antigen; however, antibody to IL-2 inhibited lymphocyte proliferation on exposure to VZV antigen. These results indicate that IL-2 and expression of IL-2R beta are essential to lymphocyte activation by VZV antigen.

Adult↗
PubMed1992

Crystallization and preliminary X-ray studies of a Bacillus subtilis and Thermus thermophilus HB8 chimeric 3-isopropylmalate dehydrogenase and thermostable mutants of it.

A new type of chimeric 3-isopropylmalate dehydrogenase (2T2M6T) was produced by expressing the fused gene of Bacillus subtilis and Thermus thermophilus. The enzyme shows heat stability intermediate between those of the parents. The crystal of the enzyme belongs to the space group of P3(2)21, with cell dimensions of a = b = 78.9 A and c = 158.9 A. Two thermostable mutants of the chimeric enzyme were prepared by site-directed mutagenesis and then crystallized.

3-Isopropylmalate Dehydrogenase↗
PubMed1992

Churg-Strauss syndrome: report of a case without preexisting asthma.

A 38-year-old male with no history of asthma, who initially presented with episcleritis and subsequently developed symptoms of systemic vasculitis with marked blood eosinophilia, was diagnosed as having Churg-Strauss syndrome (CSS). Both the patient's skin lesions and pulmonary infiltrates revealed histologically proven vasculitis with predominantly eosinophilic infiltration. All the symptoms of systemic vasculitis except the persisting peripheral neuropathy dramatically improved after corticosteroid was systemically used. Since scattered non-asthmatic cases of CSS have been reported recently, and three such patients have died of acute heart failure due to delayed diagnosis, absence of asthma should not be regarded as an absolute criterion for exclusion of the diagnosis of CSS. Earlier recognition of this disease is important, since earlier institution of steroid therapy can prevent the acute onset of fatal cardiac involvement during the course of this disease.

Adult↗
PubMed1992

Shedding of CD9 antigen by bone marrow cells from patients with acute lymphoblastic leukaemia.

The levels of soluble CD9 antigen released into spent medium from bone marrow (BM) cells were assayed using a unique enzyme-linked immunosorbent assay. We demonstrated that a considerable amount of soluble CD9 antigen was consistently detected in the spent medium from CD9+ leukaemic blasts, but little from normal or regenerating BM cells. The sensitivity and specificity of CD9 antigen assay were tested. First, BM cells taken from patients in complete morphologic remission (CR) were studied, and the distinct level of CD9 antigen was detected in 16.3% of the cases. Second, the outcome of leukaemic patients with significant shedding of CD9 antigen from BM cells while in CR was investigated: all patients have developed systemic relapse within 5-24 (median 15.4) weeks. In contrast, 24/34 patients without the increase of CD9 antigen levels are still in CR (follow-up 19-149 weeks, median 56.2 weeks). Only 10 patients in this group have relapsed so far. No false-positive results were detected with this sensitive assay for soluble CD9 antigen, and the introduction of appropriately planned prospective studies is justified on the basis of these observations.

Antigens, CD↗
PubMed1992

Expression of IL-2 receptor/p75 on lymphocytes from patients with rubella.

We analyzed the Interleukin-2 receptor (IL-2R) expression on fresh lymphocytes from three patients with rubella. Flow cytometric analysis demonstrated that lymphocytes from the patients expressed a considerable amount of IL-2R/p75 recognized by Mik-beta 1 monoclonal antibody (MoAb), although they did not react with anti-IL-2R/p55 (CD25) MoAb. The expression of IL-2R/p75 reached a peak at the end of the acute phase of illness. Fresh lymphocytes from rubella patients showed a marked proliferative response to IL-2, which was completely inhibited by Mik-beta 1, indicating that their IL-2R is a functional receptor. The present data suggest that IL-2R/p75 expression is involved in the host immune response triggered by the rubella virus.

Antibodies, Monoclonal↗
PubMed1992

Initiation and development of calcium waves in rat myocytes.

To understand the characteristics of asynchrony in spontaneously occurring increases in cytoplasmic calcium concentrations ([Ca2+]i) in the cardiac myocyte, we observed newly developed changes in regional [Ca2+]i after a physical injury to the sarcolemma. Myocytes were isolated from rat left ventricle and loaded with acetoxymethyl ester of fura-2. We analyzed dynamic changes in fluorescence images by video densitometry. After the injury was imposed, three types of responses were observed: 1) rapid contracture with steady increase in [Ca2+]i; 2) periodic development of a calcium wave; and 3) quiescence after the injury. In some myocytes with the second type of response, a sustained burst of calcium waves was observed. In myocytes in which multiple calcium waves are present simultaneously, a propagated wave can reset a cycle of wave generation at the wave focus. Waves disappear after their collision, which indicates the existence of a refractory period after the calcium transient. The wave originating from the focus with the fastest frequency dominates the whole cell. Thus dynamic changes in regional [Ca2+]i are asynchronous but are organized by the following principles: 1) a regional increase in [Ca2+]i can propagate; 2) a propagated calcium wave can reset a cycle of wave initiation at the focus; and 3) a regional calcium transient leaves a refractory period.

Animals↗
PubMed1992

Prediction of advanced puberty by height velocity in children with acute lymphoblastic leukemia.

Pubertal development was retrospectively evaluated in 58 children with cancer, mostly acute lymphoblastic leukemia (ALL), who are in complete remission and off chemotherapy. Six girls [5 patients with ALL, and 1 with malignant lymphoma (NHL)] showed advanced puberty (25.0%, 6 of 24 female patients with ALL and NHL) through the evaluation of their growth velocity. No evidence for advanced puberty was seen in the males. All 6 girls had received cranial irradiation for central nervous system prophylaxis and systemic chemotherapy including glucocorticoid. The mean age at onset of the pubertal growth spurt in these 6 girls was significantly lower than for girls with a solid tumor [6.90 +/- 0.10 and 9.00 +/- 0.77 (mean +/- SD) years, respectively (p < 0.01)]. By simply evaluating the height velocity, we could predict advanced puberty which was ultimately associated with short stature.

Adolescent↗
PubMed1992

Lidocaine unmasks silent demyelinative lesions in multiple sclerosis.

Blockage of a small number of sodium channels may prevent impulse conduction in some demyelinated segments of nerve fibers with low safety factors, thereby unmasking subclinical demyelinative lesions. On the basis of this hypothesis, lidocaine, a sodium channel blocker, was administered intravenously to 28 MS patients and to 19 normal subjects and seven patients with nondemyelinating diseases. As predicted, lidocaine (mean plasma level, 2.7 micrograms/ml) elicited reversible subclinical symptoms in 23 of the MS patients, but it had not effect on the control subjects. We made a quantitative study of the visual functions (visual acuity, color vision, visual evoked potential [VEP]) that were impaired in 15 MS patients. Of the 23 affected eyes, nine showed normal VEPs, indicative of the test's sensitivity to focal lesions. This test should be useful in the diagnosis of MS and in the evaluation of the subclinical activity of MS as well.

Adult↗
PubMed1992

[The effect of etoposide on influx and efflux of cytosine arabinoside in P388 murine leukemic cells].

We studied the effects of etoposide on the influx, intracellular accumulation and efflux of ara-C in P388 leukemic cells. Etoposide inhibited the active influx of ara-C in a dose dependent manner, and the inhibition was reversible. Etoposide also affected the intracellular accumulation of ara-C, though its inhibitory effect for the intracellular accumulation was weaker than that for the influx of ara-C. It was also shown that etoposide inhibited the active efflux of ara-C. Furthermore, etoposide inhibited the active transport of ara-C bidirectionally but the insensitive route of etoposide existed especially at high concentration of ara-C. The effect of inhibition of the transport of ara-C on the accumulation of ara-C was more significant at lower concentration of ara-C. Judging from the drug concentrations used in this study, an interaction between etoposide and ara-C could occur in the clinical treatment.

Animals↗
PubMed1992

Tissue distribution of 125I-labeled fetal thyroid hormone in nude mice xenografted with Ewing sarcoma.

Biodistribution of fetal thyroid hormone (RT3) was studied in nude mice with Ewing's sarcoma xenografts. At 30 min and 1, 2, 4, 8, and 12 hr after injection, blood, tumor and normal organs were measured to determine the amount of radioactivity per gram of tissue. The amount of radioactivity in the blood of tumor-bearing mice decreased sharply from 7.64% of injected dose per gram of tissue (% ID/g) at 30 min after inoculation to 0.45%/ID/g at 12 hr. The % of injected dose per gram for 125I-labeled RT3 in the tumor reached 1.92 at 1 hr after injection and decreased to 0.22 at 12 hr. The radiolocalization indices for tumor to other organs at 12 hr ranged from 1.35 to 4.43. This study suggests increased localization of RT3 in the Ewing's sarcoma as compared to other tissues in the nude mouse.

Animals↗