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Biomedical subjects

Y Ohba

Publications and source records attributed to Y Ohba.

At least 73 records · Page 4Linked to original sources
PubMed1998

Molecular cloning of the rat Tpx-1 responsible for the interaction between spermatogenic and Sertoli cells.

We previously showed in a primary culture of rat testicular cells that spermatogenic cells specifically bind to somatic Sertoli cells and that this interaction is needed for spermatogenic cells to differentiate in vitro. Adopting an expression cloning procedure, we here isolated a cDNA coding for a spermatogenic cell protein whose expression gave a cultured cell line the ability to bind to Sertoli cells. The protein, 243 amino acids with a putative N-terminal signal peptide and a C-terminal Cys-rich region, turned out to be the rat homologue of a testicular protein called Tpx-1 whose function had yet to be determined. A polyclonal antibody raised against bacterially expressed Tpx-1 significantly inhibited the binding of spermatogenic cells to Sertoli cells. The above results indicated that Tpx-1 is a testicular cell adhesion molecule responsible for the specific interaction between spermatogenic and Sertoli cells.

Amino Acid Sequence↗
PubMed1998

Novel physiological functions of cathepsins B and L on antigen processing and osteoclastic bone resorption.

Lysosomal cathepsin B plays an essential role in the processing of ovalbumin as an exogenous antigen to produce the complex between antigenic-peptide and major histocompatibility-complex class II. Administration of cathepsin B inhibitors, E-64, CA-074 and vitamin B6, caused the strong suppression of the Th-2 type immune responses. We found that pyridoxal phosphate (PAP), a coenzyme form of vitamin B6, inhibits the activities of cathepsin B and L in vitro and vitamin B6 administration induces the inhibition of the lysosomal cathepsin activities in vivo. The production of an antigenic epitope (I323-R339) of ovalbumin by antigen presenting cells was suppressed by cathepsin B specific inhibitors. The ovalbumin dependent production of immunoglobulins (IgE and IgG1) and of the corresponding interleukin (IL-4) was suppressed by cathepsin B inhibitors, while the production of IgG2a and interferon (INF-gamma) was increased. The switch of helper T lymphocyte functions from the type-2 to the type-1 may be induced by the cathepsin B inhibition. The experimental bone pit formation, i.e., osteoclastic bone collagen degradation test, induced by parathyroid hormone was markedly suppressed by the administration of pyridoxal, because of the inhibition of cathepsin L type cysteine proteases in bone.

Animals↗
PubMed1998

Co-expression of Fas and Fas-ligand on the surface of influenza virus-infected cells.

Influenza virus-infected cultured cells undergo apoptosis after an increment of Fas (APO-1/CD95) on the cell surface. By flow cytometry, cell surface Fas-ligand was detected in virus-infected cells with a time course similar to that of Fas. Moreover, Fas and Fas-ligand were co-expressed in those cells. The mode of induction, however, appeared to be distinct for the two proteins. Influenza virus infection induced the externalization of phosphatidylserine on the cell surface at the early stage of apoptosis, an event that has been observed in cells undergoing Fas-mediated apoptosis. In fact, apoptosis of the virus-infected cells was inhibited in the presence of an antagonistic anti-Fas-ligand monoclonal antibody. These results suggest that influenza virus infection causes augmented expression of both Fas and Fas-ligand and apoptosis is induced when the infected cells come into contact with each other.

Annexin A5↗
PubMed1998

Thyroid hormone, all-trans retinoic acid, and 9-cis retinoic acid functioned as negative modulators of the effect of glucocorticoid on induction of alpha 1-acid glycoprotein mRNA in RLN-10 cells.

The expression of acute-phase protein genes is controlled by many factors, such as IL-1, IL-6, glucocorticoids, thyroid hormone (T3), and retinoic acids. We studied the interaction of T3, glucocorticoids, all-trans retinoic acid (RA), and 9-cis retinoic acid (9cRA) on the expression of the rat alpha 1-acid glycoprotein (AGP) gene in vitro. Dexamethasone (Dex) activated AGP gene expression in a rat liver derived cell line, RLN-10. Although T3, RA, and 9cRA by themselves had no effect on AGP production, they reduced the response to Dex of the AGP gene.

Alitretinoin↗
PubMed1998

Radiofrequency catheter ablation of left ventricular outflow tract tachycardia: report of two cases.

Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. We report two patients whose QRS configuration during VT commonly showed an inferior axis and monophasic R waves in all the precordial leads. The mechanism of these VTs appeared to be triggered activity. From mapping and ablation, the origin of these VTs was determined to be in the most posterior LVOT, corresponding to the aortomitral continuity (left fibrous trigone).

Catheter Ablation↗
PubMed1998

[Diagnosis of hemoglobinopathies].

The chemical identification of variant hemoglobins was largely overtaken by DNA analysis during the last decade, despite remarkable improvement and automation of individual procedures in conventional chemistry. DNA diagnosis has proved more versatile, covering both variant hemoglobin and thalassemia mutations, less labor-demanding, and easier to learn. Protein chemistry is now reserved for some special problems such as post-translational modification (this problem would be covered much better by mass spectrometry), biosynthesis and stability, and pathologic physiology of selected abnormal hemoglobins. After introduction of DNA analysis during mid 1980's, the number of blood samples referred to our laboratory rapidly increased, mainly because of thalassemia traits in the differential diagnosis of microcytic anemia. Our experience during the past forty years and the present strategy for the rapid presumptive diagnosis of hemoglobinopathies and precise identification of mutations are briefly summarized.

DNA↗
PubMed1998

[Appropriate laboratory use of microbiological testing for quality control and nosocomial infection control].

Useful information from clinical microbiological tests is required for clinical diagnosis and treatment of infectious disease, whereas concern about the quality of information is still low. To provide reliable information in clinical microbiological testing, it is necessary to control the quality of clinical specimens, because of its random character. Through effective use of laboratory testing database, it will be possible to shift away our vague management of pre-analytic phase of quality control so far to its established system based on objective evaluation. During the past 4 years, after the introduction of microbiological tests and information system in our hospital, the characteristics of sputum have become worse contrary to our expectations. This suggests that quality control needs successive improvements, even in service departments such as clinical laboratories. Application of laboratory testing database to nosocomial infection control is considered to be a performance of post-analytic phase of quality control from the viewpoint of effective use of laboratory data. We presented in this paper our practical application of the database to the short-term and long-term control of nosocomial infection.

Clinical Laboratory Information Systems↗
PubMed1997

Analysis of chromatin structure of rat alpha1-acid glycoprotein gene; changes in DNase I hypersensitive sites after thyroid hormone, glucocorticoid hormone and turpentine oil treatment.

Transcription of the ratalpha1-acid glycoprotein (AGP) gene is activated by glucocorticoid, thyroid hormone (T3) and cytokines. Following these treatments, the chromatin structure of this gene was analyzed by means of digestion with DNase I or micrococcal nuclease. Four DNase I hypersensitive sites were observed in the 5'-upstream region of the rat AGP gene of liver cells. They were designated HS1, HS2, HS3 and HS4 (3'-->5'). After T3treatment the sensitivity of HS1 and HS2 increased and after dexamethasone (Dex) treatment that of all four sites did so. Three new sites appeared after turpentine oil treatment, while the sensitivities of HS3 and HS4 increased. We conclude that transcriptional activation of the gene by T3and Dex have very similar mechanisms, but that at the inflammation stage they become slightly different. The increase in sensitivity at HS1 and HS2 after T3treatment in vivo was successfully reproduced in a cell-free system by in vitro treatment with T3. HS1, HS2 and HS3 were also sensitive for micrococcal nuclease.

Animals↗
PubMed1997

Recognition of phosphatidylserine on the surface of apoptotic spermatogenic cells and subsequent phagocytosis by Sertoli cells of the rat.

In a primary co-culture of spermatogenic and Sertoli cells of the rat, many spermatogenic cells die by apoptosis and are subsequently engulfed by Sertoli cells. We investigated the mechanism of this phagocytosis reaction. Testicular cells from 20-day-old rats were cultured, and spermatogenic cells and Sertoli cells were separated. When the recovered spermatogenic cells were maintained without Sertoli cells, the viability of the cells decreased and they became more susceptible to phagocytosis by Sertoli cells. Phagocytosis was severely impaired when liposomes containing acidic phospholipids, such as phosphatidylserine, phosphatidylinositol, and cardiolipin, were included in the reaction, whereas those consisting of neutral phospholipids showed little effect. Such anionic liposomes were more efficiently engulfed by Sertoli cells than were the other neutral liposomes. Also, the number of spermatogenic cells that exposed phosphatidylserine to the surface increased when cells were maintained in single culture. The results indicate that upon induction of spermatogenic cell apoptosis, phosphatidylserine and probably other acidic phospholipids, which are normally localized in the inner leaflet of the plasma membrane, translocate to the outer leaflet and serve as a signal for phagocytosis by Sertoli cells.

Animals↗
PubMed1997

14-3-3 zeta protein binds to the carboxyl half of mouse wee1 kinase.

To identify proteins which bind to mouse wee1 kinase, the yeast "two-hybrid" system was used with a mouse cDNA library. Using the carboxyl half of weel kinase, the 14-3-3 zeta protein was isolated. Recombinant 14-3-3 zeta was demonstrated to bind to wee1 kinase in vitro. The wee1 kinase phosphorylated by cdc2 kinase also bound to 14-3-3 zeta protein. When both wee1 kinase and 14-3-3 zeta were transfected into COS-1 cells, they formed a complex in a cell. The sequence of wee1 kinase necessary for the binding was tested by a two hybrid system expressing different lengths of peptides derived from wee1 kinase. Both the entire kinase domain and a sequence in the carboxyl terminus was thought to be necessary for the binding. The function of 14-3-3 zeta protein remained to be elucidated in relation to the regulation of G2 to M phase transition through wee1 kinase.

14-3-3 Proteins↗
PubMed1997

Prodigiosin 25-C and metacycloprodigiosin suppress the bone resorption by osteoclasts.

Prodigiosin 25-C and metacycloprodigiosin were found to suppress PTH-stimulated pit formation by cultured osteoclasts on bone slices. They also inhibited the acidification of vacuolar organelles in intact osteoclastic cells. Since the acidic pH in these organelles is generated by the action of proton-pumping ATPases of the organelle, these results indicate that the proton-pumping activity of V-ATPase in osteoclastic cells is essential in bone resorption and that the inhibition of the acidification of vacuolar organelles by prodigiosins results in suppression of PTH-stimulated bone resorption.

Animals↗
PubMed1997

Efficacy of monotherapy with benazepril, an angiotensin converting enzyme inhibitor, in dogs with naturally acquired chronic mitral insufficiency.

Benazepril (BP), an angiotensin convertive enzyme inhibitor, was administered orally once daily for 4 weeks to 31 dogs with mild to moderate (NYHA functional classes II and III) congestive heart failure caused from mitral insufficiency (MI). There were no significant changes in clinical signs, electrocardiogram findings, radiographical observations and plasma biochemical results in 11 dogs treated with placebo for 4 weeks. In 31 dogs treated with BP, appetite increased, and mean scores of heart failure signs, such as activity, exercise tolerance, cough and respiratory effort, were significantly improved. No dog displays signs suggesting systemic hypotension. One dog died suddenly on the 26th day of treatment with BP. This dog had good vigor and appetite till the evening before the death, and cough and exercise tolerance had been gradually improving. The heart rate and ECG parameters of BP treated dogs did not change significantly, but length of long axis of the heart decreased. In plasma biochemical tests, plasma urea nitrogen (UN) levels did not change significantly, and plasma creatinine (CRE) levels increased slightly within the normal ranges during BP trial. Two dogs had higher plasma UN levels with slightly higher plasma CRE levels, but had normal general condition and other biochemical results. Plasma ACE activity decreased to 57.3% of pre-treatment level at 4 weeks after BP treatment. It is concluded that BP monotherapy was efficacious at least in dogs with relatively low grade congestive heart failure caused by MI.

Administration, Oral↗
PubMed1997

Morphological and flow cytofluorometrical analyses of regenerated rat thymus after irradiation.

Reconstituted rat thymuses were studied by immunohistochemistry, transmission electron microscopy (TEM) and flow cytofluorometry on days 0, 1, 2, 3, 5, and 7 after whole-body sublethal irradiation (6 Gy). One day after irradiation, numerous apoptotic cells were seen in the cortical thymus; the percentage of the sub-G1 peak representing apoptotic cells was 8.9% in the DNA content histogram of cytofluorometry. On day 3, the thymic structure had been destroyed and no distinction was drawn between the cortex and medulla. In this stage, few thymocytes but many macrophages were present, and the percentage of the sub-G1 peak reached a peak at 13.0%. Bromodeoxyuridine (BrdU) incorporated cells gradually increased after irradiation, and immunohistochemically numerous apoptotic cells were found primarily in the cortex on day 7. These thymocytes showed some levels of electron density of the nucleus as revealed by TEM. The percentage of S phase cells did not change markedly (20-30%) based on one-color DNA content histograms, but the percentage of early S and S phase cells was extremely high on day 7 (70%). These data indicate that a part of DNA synthetic cells may result in apoptosis. The combination of immunohistochemistry, TEM and flow cytofluorometry to analyze DNA content and BrdU incorporation proved a useful tool for investigating the reconstituted thymus.

Animals↗
PubMed1997

Transcripts containing the sea urchin retroposon family 1 (SURF1) in embryos of the sea urchin Anthocidaris crassispina.

We isolated two cDNAs, termed D7 and C2 in the present study, from a cDNA library of the 16-cell embryo of the sea urchin Anthocidaris crassispina. The nucleotide sequence was determined completely for D7, and partially for C2. D7 does not have any significant open reading frames. Both D7 and C2 contain a common sequence that is 62% homologous to the sea urchin retroposon family 1 (SURF1). The SURF1 is a short interspersed repetitive element identified from the sea urchin Strongylocentrotus purpuratus, and is reported to be transcribed by RNA polymerase III. The structural feature of D7 and C2, however, suggests that they may be transcribed by RNA polymerase II. RT-PCR analyses revealed that (1) both D7 and C2 transcripts exist as a maternal RNA in the egg, (2) they appear evenly distributed in the 16-cell embryo, and (3) C2 transcripts are present throughout the development up to the gastrula, while D7 transcripts decrease in amount after the early cleavage stage.

Animals↗