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Biomedical subjects

K Dobashi

Publications and source records attributed to K Dobashi.

At least 145 records · Page 8Linked to original sources
PubMed1988

Novel antifungal antibiotics octacosamicins A and B. I. Taxonomy, fermentation and isolation, physico-chemical properties and biological activities.

Two antifungal antibiotics octacosamicins A and B were isolated from the culture broth of a strain of actinomycetes, which was identified as a strain of Amycolatopsis. These antibiotics were isolated by resin adsorption and purified by column chromatography and preparative HPLC. Both antibiotics were found to be new substances from their physico-chemical properties. They showed broad antifungal spectra.

Actinomycetales↗
PubMed1988

Novel antifungal antibiotics octacosamicins A and B. II. The structure elucidation using various NMR spectroscopic methods.

The structures of octacosamicins A and B, two new antifungal antibiotics, were studied by spectrometries and chemical modifications. The 2D NMR techniques including 1H-detected heteronuclear multiple bond correlation method were successfully applied to this study. These antibiotics have unique linear chain structure possessing N-hydroxyguanidyl group at the terminal.

Antifungal Agents↗
PubMed1988

The role of the neu oncogene product in cell transformation and normal development.

p185neu, the protein product of the neu gene, is a tyrosine kinase receptor with structural similarity to the epidermal growth factor (EGF) receptor. The cognate ligand for the p185neu receptor remains unknown. We have defined: 1) stage and tissue-specific expression patterns of the neu gene product in developing tissues; 2) p185neu phosphorylation and the regulation of p185neu tyrosine kinase activity by EGF. 3) Synergistic interactions of cellular rat p185neu and EGF receptor leading to cell transformation; 4) structural and functional differences of normal and oncogenic p185neu. These observations explain some features of how p185neu is involved in normal development and neoplastic transformation.

Animals↗
PubMed1988

[Right aortic arch with isolation of the left subclavian artery. A case report].

A 58 year old man was admitted to evaluate his swallowing disturbance. Preoperative aortogram demonstrated right aortic arch with isolation of left subclavian artery. Operative findings revealed the absent blood flow through the proximal portion of left subclavian artery which connected to the left pulmonary artery. Abnormal connection was divided and Kommerell's diverticulum was mobilized from the esophagus. His clinical symptom was slightly reduced postoperatively.

Aorta, Thoracic↗
PubMed1988

T-cell-derived factor B151-TRF1/IL-5 activates blastoid cells among unprimed B cells to induce a polyclonal differentiation into immunoglobulin M-secreting cells.

Two distinct murine B-cell differentiation factors, designated B151-TRF1 and B151-TRF2, were described originally as B151K12 T-cell hybridoma-derived lymphokines that induce immunoglobulin (Ig) secretion by antigen-activated B cells and unstimulated B cells, respectively. In the present study, we found that a highly purified B151-TRF1 fraction prepared by reversed-phase high-performance liquid chromatography (RP-HPLC) also has the ability to cause a polyclonal differentiation of unstimulated B cells into IgM-secreting cells in the apparent absence of co-stimulant. The activity of the B151-TRF1 fraction but not the B151-TRF2 fraction on unstimulated B cells was markedly inhibited by addition of a monoclonal antibody (mAb) specific for the B151-TRF1/IL-5 to the culture. To determine whether B151-TRF1/IL-5 and B151-TRF2 act on distinct populations among unstimulated B cells, the responsiveness of neonatal B cells and adult B cells that had been fractionated by Percoll density gradient centrifugation was assessed. B151-TRF1/IL-5 predominantly acted on lower density B cells, which appeared around 3 weeks after birth in the spleen. In contrast, B151-TRF2 could activate both lower and higher density B cells almost equally and B151-TRF2-responsive B cells were already present by 1 week of age. Thus, these results suggest that B151-TRF1/IL-5 and B151-TRF2 act on distinct subpopulations among antigen-unprimed normal B cells to induce IgM-secreting cells.

Animals↗
PubMed1988

[A histologic and functional evaluation of non-villous trophoblasts in the basal plate of human placenta].

This investigation of trophoblasts (Trs) in early gestation was performed by histologic and immunohistochemical evaluation of the Trs of the basal plate, decidua and myometrium, in an attempt to determine the changes in structure and function dependent on their location. The structural evaluation was performed by both light and electron microscopy and the functional evaluation by the localization of hCG, its subunits and hPL. In the syncytiotrophoblastic cell layer both hCG, its subunits and hPL are localized intracellularly. In the decidua, the so-called invasive Trs, only hPL could be detected. Histologically, the Trs in the deeper decidua tend to coalesce and become multinucleated. Thus, villous Trs and invasive Trs differ not only structurally, but also functionally, as can be seen by the differences in the synthesis of hCG and hPL, leading to the assumption that Trs have varying functions dependent upon their location.

Chorionic Gonadotropin↗
PubMed1987

Polyclonal B cell activation by a B cell differentiation factor, B151-TRF2. III. B151-TRF2 as a B cell differentiation factor closely associated with autoimmune disease.

We demonstrated previously that B151K12 T cell hybridoma produces two distinct B cell differentiation factors, B151-TRF1 and B151-TRF2, capable of inducing differentiation of antigen-activated and unstimulated B cells into antibody-forming cells, respectively. In the present study we investigated the pathophysiologic relation of these factors with factors obtained from MRL/MP-lpr/lpr(MRL/lpr) mice and (C57BL/6 X DBA/2)F1 (BDF1) mice undergoing chronic graft-vs-host reaction (GVHR), representing a murine model of systemic lupus erythematosus with polyclonal B cell activation associated with the T cell hyperfunction. The functional and biochemical analyses revealed that B151-TRF2-like, but not B151-TRF1-like, activity was found in culture fluid supernatant (CFS) of lymphoid cells from MRL/lpr mice with lymphoproliferative syndrome. On the other hand, both B151-TRF1- and B151-TRF2-like activities were detected in CFS prepared from spleen cells of BDF1 mice undergoing chronic GVHR by the inoculation of parental DBA/2 spleen cells. Interestingly, spleen cells of BDF1 mice transferred with DBA/2 thymocytes preferentially elaborated B151-TRF1-like factor. Because BDF1 mice transferred with DBA/2 spleen cells but not with DBA/2 thymocytes developed a SLE-like syndrome exemplified by the appearance of Coombs' antibody and proteinuria, it seemed likely that production of B151-TRF2-like factor was closely associated with the onset of autoimmune disease. In fact, B151-CFS containing B151-TRF2 but not B151-TRF1 activity could induce a striking autoantibody production both in vivo and in vitro as detected by PFC responses of normal mice to bromelain-treated mouse red blood cells (BrMRBC). Moreover, it was demonstrated that in vitro anti-BrMRBC PFC responses induced by semipurified B151-TRF2 was markedly inhibited by addition of relevant anti-Ia antibody to the culture. Thus, the present study demonstrates that B151-TRF2 represents one of the B cell differentiation factors responsible for polyclonal B cell activation leading to autoantibody production.

Animals↗
PubMed1987

Lipid peroxidation and free radical scavengers in thyroid dysfunction in the rat: a possible mechanism of injury to heart and skeletal muscle in hyperthyroidism.

This study was designed to determine if peroxidation of biomembrane lipid and the protective system can be modified by the change in oxidative metabolism induced by thyroid dysfunction. The free radical scavengers (i.e. cuprozinc cytosolic and mangano mitochondrial superoxide dismutases, glutathione peroxidase, and catalase), mitochondrial oxidative marker enzymes (cytochrome c oxidase and fumarase), and lipid peroxide were measured in liver, heart, soleus (slow oxidative), and extensor digitorum longus (fast glycolytic) muscles. Rats were rendered hyper- or hypothyroid for 4 weeks and then killed. Superoxide dismutases were detected by specific RIAs: catalase by polarography, and lipid peroxide by fluorimetry. Hypothyroid rats failed to grow, while hyperthyroid rats had hypertrophied hearts but no growth failure. An increase in lipid peroxide was observed in the soleus and heart muscles of hyperthyroid rats. This was accompanied by an increase in mitochondrial superoxide dismutase and oxidative markers. No such change was observed in either fast glycolytic muscle or liver. Glutathione peroxidase decreased in all tissues of hyperthyroid rats, and there was a parallel decrease in catalase in most tissues. On the other hand, hypothyroidism induced a reduction in oxidative markers and mitochondrial superoxide dismutase in heart and skeletal muscles, but only a marginal change in lipid peroxidation. The cytosolic superoxide dismutase did not change in relation to either oxidative metabolism or lipid peroxidation. These results suggest that the enhanced oxidative metabolism and decreased glutathione peroxidase in hyperthyroidism result in an increase in lipid peroxidation and, in slow oxidative and heart muscle, possible organ damage. No adverse reaction mediated by active oxygen species was found in hypothyroid rat tissues.

Animals↗
PubMed1986

Identification of two distinct factors, B151-TRF1 and B151-TRF2, inducing differentiation of activated B cells and small resting B cells into antibody-producing cells.

We demonstrated previously that cellfree supernatant of the B151K12 T cell hybridoma (B151-CFS) contained T cell-replacing factor (here in after referred to as B151-TRF1) capable of inducing growth and differentiation of antigen-activated B cells into antigen-specific plaque-forming cells (PFC). In the present study, we have identified in B151-CFS another unique lymphokine activity (referred to as B151-TRF2), which induces polyclonal differentiation of unstimulated B cells into IgM-secreting cells without concomitant stimulation of antigen, mitogen, or anti-Ig antibody. The B151-TRF2 activity induced polyclonal IgM PFC responses via the action on surface Ig-positive small resting B cells from normal unprimed mice. This activation was effective across an H-2 barrier, and apparently independent of the presence of T cells and accessory cells. Interestingly, the B151-TRF2 activity notably stimulated B cells of neonatal and mutant DBA/2Ha mice, which are nonresponders to B151-TRF1, whereas it failed to activate the xid B cells from CBA/N mice. To substantiate that B151-TRF1 and B151-TRF2 activities are mediated by mutually distinguishable molecules, an absorption experiment of B151-CFS was performed by utilizing DBA/2Ha B cells which are lacking in B151-TRF1 receptor. It was found that DBA/2Ha B cells could absorb B151-TRF2 activity but not B151-TRF1 activity. In contrast, murine chronic B cell leukemia BCL1 cells, which were shown to differentiate into IgM-secreting cells by stimulation with B151-CFS, selectively removed B151-TRF1 activity but not B151-TRF2 activity. Furthermore, biochemical analysis revealed that the B151-TRF2 was a heat (56 degrees C for 30 min)-sensitive protein with an apparent m.w. of 30,000 by gel filtration, whereas B151-TRF1 was a heat-resistant glycoprotein with m.w. of 50,000. In addition, it was shown that prostaglandin E2 selectively inhibited B151-TRF2-mediated B cell responses. These results demonstrate clearly that B151-TRF1 and B151-TRF2 are distinct B cell differentiation factors involved in the different activation pathways of distinct B cell subpopulations. The immunologic implication of B151-TRF2 activity in B cell differentiation is discussed in comparison with other lymphokines so far reported to activate small resting B cells.

Animals↗
PubMed1986

Quantitative nuclear DNA analysis of human ovarian adenocarcinoma: compared before and after chemotherapy and correlated with clinical response.

Quantitative DNA measurements on 18 human ovarian adenocarcinomas were made by computerized image analysis. The DNA content of the tumor cells was measured on specimens of tumor obtained at the initial diagnostic surgery and at second-look surgery after treatment with chemotherapy. The mean DNA content of the specimens and the ploidy pattern of the tumor cells were determined. With the exception that borderline tumors had near normal ploidy patterns and mean DNA content, there was no consistent correlation between the stage of disease, grade, or histiologic character of the tumor and either the DNA content or ploidy pattern. But it was noteworthy that all three of the patients who had complete responses (negative second-looks), also had tumors with DNA content and ploidy patterns near triploid. When the ratio of mean DNA content before and after chemotherapy was determined for each ploidy group, there was an apparent correlation between this ratio and clinical status of the patient 10 month after chemotherapy. That is, patients with low ploidy tumors and high DNA content ratio (greater than 1.25) had a better prognosis than patients with high ploidy tumors and lower DNA content ratios (less than 1.25). Thus, although the mean DNA content of the tumor at the initial surgery was not in itself of sufficient prognostic value, when the mean DNA content of the tumor after chemotherapy is also known, an accurate picture of the patients clinical response could be determined.

Adenocarcinoma↗
PubMed1986

Accurate laboratory predictions of the clinical response of patients with advanced ovarian cancer to treatment with cyclophosphamide, doxorubicin, and cisplatin.

Seventy-six patients with advanced ovarian cancer treated with cyclophosphamide, doxorubicin, and cisplatin (CAP) at 3-week intervals were tested for the response of their tumors to treatment with CAP in the subrenal capsule tumor implant assay. Thirty-four of the patients' tumors were assayed prospectively before clinical treatment and 33 were assayed retrospectively, after clinical treatment with CAP. Nine of the patients' tumors were assayed both prospectively and retrospectively. All of the patients underwent a tumor debulking laparotomy. Of the patients with clinically measurable residual disease, 17 had a partial response of at least 50% regression of disease, and 11 had a progression of disease. Of the patients with known residual but nonmeasureable disease, 7 had surgically verified complete responses, 8 at least 50% regression, and 23 had progression of disease: 10 had no evidence of disease clinically but had not had surgical confirmation. Twenty-six of the tumors were adenocarcinomas not otherwise specified (2 grade I, 2 grade II, and 22 grade III), 39 were serous adenocarcinomas (7 grade I, 9 grade II, and 23 grade III), 7 were endometrioid adenocarcinoma (all grade III), 3 were mucinous adenocarcinomas (1 each of grade I, II, and III) and 1 was an adenosquamous carcinoma (grade III). Thirty-four of the patients failed the therapy. The subrenal capsule (SRC) assay predicted 21 of these failures (4 prospective and 17 retrospective). Thirty-two of the patients responded to CAP chemotherapy. The SRC assay accurately predicted the clinical regression of the tumors of 22 of the patients (15 prospective and 7 retrospective). Second-look laparotomy confirmed 7 patients with no evidence of disease, 5 patients with minimal disease, and 5 patients with a greater than 50% reduction of their disease. The SRC assay predicted the response of all these patients except 2 with partial responses to chemotherapy. Thus, while the overall positive predictive value of the SRC assay in this study is 65%, it is 100% for those patients whose tumors respond completely and for those who have minimal residual disease after CAP chemotherapy.

Animals↗
PubMed1985

A new radioimmunoassay for serum 16 alpha-hydroxyandrost-4-ene-3,17-dione with specific antiserum.

A radioimmunoassay system for serum 16 alpha-hydroxyandrost-4-ene-3,17-dione was developed with the use of rabbit antiserum against 16 alpha-hydroxyandrost-4-ene-3,17-dione-3-(O-carboxymethyl)oxime which was conjugated with bovine serum albumin. The antiserum was highly specific for 16 alpha-hydroxyandrost-4-ene-3,17-dione, with cross reactions to other steroids being less than 0.8% except for androst-4-ene-3,17-dione(3.4% cross reaction). Use of LH-20 column chromatography, however, clearly separated these two steroids. Pregnancy sera were measured with this assay system after an addition of labelled internal standard, extraction and separation by column chromatography. The lower limit of detection for 16 alpha-hydroxyandrost-4-ene-3,17-dione was 2 pg/tube. The mean recovery rate of the added standard was 98.3 +/- 8.8% (mean +/- SE). Intra- and inter-assay coefficients of variation were 8.6% (n = 6) and 12.1% (n = 7), respectively.

Amniotic Fluid↗
PubMed1985

Purification and physicochemical characterization of murine T cell replacing factor (TRF).

Murine T cell replacing factor (TRF) was purified from a cellfree supernatant of a T cell hybridoma (B151K12) that constitutively produces TRF. Two assay systems for TRF activity were employed: 1) induction of anti-DNP IgG PFC responses in cultures of splenic B cells from DNP-KLH-primed BALB/c mice, and 2) induction of IgM PFC in chronic B cell leukemic cells (BCL1). The purification scheme consisted of ammonium sulfate precipitation, DEAE-cellulose chromatography, Blue-Sepharose chromatography, hydroxylapatite chromatography, gel permeation with fast protein liquid chromatography (FPLC), and disc polyacrylamide gel electrophoresis. Overall, TRF was purified approximately 34,000-fold with a maximum 3.8% recovery of activity, and the specific activity of the purified TRF was approximately 9.6 X 10(4) U/mg. The TRF that is active in these systems is distinct from the other lymphokines such as IL 1, IL 2, BCGFI (now known as BSFp1), and gamma-interferon. The TRF is extremely hydrophobic, with an apparent m.w. of 50,000 to 60,000 on gel permeation chromatography and 18,000 on SDS-PAGE under reducing conditions. Highly purified B151-TRF abrogated the activity by treatment with trypsin but not with RNase. Moreover, it bound to lima bean agglutinin-Sepharose specific for N-acetylgalactosamine residues, indicating that B151-TRF is a glycosylated glycoprotein containing N-acetylgalactosamine residues. The role of N-acetylgalactosamine residues on TRF activity was additionally substantiated by the fact that the addition of appropriate amounts of N-acetylgalactosamine in the assay systems for TRF preferentially induced a profound suppression for TRF-mediated PFC responses.

Adjuvants, Immunologic↗
PubMed1985

Role of N-acetyl-D-galactosamine residue on B151K12-derived T cell-replacing factor (B151-TRF) molecule in B cell-receptor binding and -stimulating activity.

The role of sugar moiety on T cell-replacing factor molecule derived from a monoclonal T cell hybridoma B151K12 (B151-TRF) was analyzed with respect to the interaction with receptor on B cells. The induction of B cell differentiation into Ig-secreting cells by B151-TRF was specifically inhibited by addition of N-acetyl-D-galactosamine (GalNAc) to culture. Such inhibition appeared to be attributed to the interference of GalNAc in the interaction of TRF with its receptor, because absorption of TRF activity with B cells was notably inhibited by the presence of GalNAc. To substantiate this point further, we established binding assay of B151-TRF molecule to the receptor on B cells by using 125I-labeled TRF fraction enriched by reversed-phase high-performance liquid chromatography and gel filtration. The results revealed that the binding of 125I-TRF molecule to the B cells was almost completely blocked by GalNAc. Moreover, the existence of GalNAc residue(s) on B151-TRF molecule was evidenced by the facts that 1) the TRF activity was eluted from lectin gels with specificity for GalNAc as revealed by the functional assay, and 2) the 125I-TRF molecule specifically bound to such lectin gels. Thus, the GalNAc residue(s) on B151-TRF molecule plays an important role in binding of TRF molecule to the receptor and in the stimulation of B cells. The molecular properties of B cell-stimulatory B151-TRF and its mode of interaction with corresponding receptor on B cells were discussed in the context of B151-TRF as a glycosylated lymphokine molecule and B151-TRF receptor as a carbohydrate-binding protein (animal lectin).

Absorption↗