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Biomedical subjects

K Ochiai

Publications and source records attributed to K Ochiai.

At least 109 records · Page 6Linked to original sources
PubMed1997

Butyric acid-induced apoptosis of murine thymocytes, splenic T cells, and human Jurkat T cells.

The purpose of this study was to examine the effect of butyric acid, an extracellular metabolite from periodontopathic bacteria, on apoptosis induction in murine thymocytes, splenic T cells, and human Jurkat T cells. Butyric acid significantly suppressed T-cell viability in both a concentration- and time-dependent fashion. The results of DNA fragmentation assay indicated that butyric acid rapidly induced apoptosis in thymocytes (with 1.25 mM butyric acid and 6 h after treatment) and in splenic T cells and Jurkat cells (with 2.5 mM butyric acid and 16 h after treatment). Incubation of thymocytes or Jurkat cells with 5 mM butyric acid for 21 h resulted in the typical ladder pattern of DNA fragmentation. Furthermore, Jurkat cells treated with 5 mM butyric acid showed the characteristic pattern of apoptotic cells such as chromatin condensation and hypodiploid nuclei. Experiments with fractionated subpopulations of splenic T cells revealed that DNA fragmentation was predominantly observed in CD4+ T cells. Butyric acid-induced apoptosis of thymocytes was decreased by the protein kinase inhibitors H7 and staurosporine. These inhibitors were less effective with similarly treated splenic T cells and Jurkat cells. These data suggest that butyric acid, one of the volatile fatty acids produced by periodontopathic bacteria and one that easily penetrates the oral mucosa, can modulate the immunoregulatory cell population in periodontal tissue by inducing T-cell death through apoptosis.

Animals↗
PubMed1997

Apocrine gland tumor of the eyelid in a dog.

A 13-year-old male Shetland Sheepdog with progressive exophthalmos had a neoplastic mass in the ocular adnexa. Histologically, this neoplasm was composed of duct-forming epithelial cells with decapitation secretion. Tumor cells invaded the globe through the tunica conjunctiva and replaced the vitreous body. The cornea, iris, ciliary body, and retina were extensively destroyed. Both the epithelial and spindle-shaped myoepithelial cells showed nuclear atypia and mitotic activity in the globe. The primary tumor was diagnosed as adenocarcinoma, probably originating from apocrine sweat glands of the eyelid, and the infiltrating intraocular neoplasm was diagnosed as a malignant mixed tumor.

Adenocarcinoma↗
PubMed1997

[Studies on 5-lipoxygenase inhibitors. Synthesis of and structure--activity relationship in p-hydroxyarylalkenylbenzoazoles].

In a previous paper we reported that 2-(p-hydroxyarylbutadienyl)benzoxazoles are highly potent 5-lipoxygenase inhibitors. We synthesized their ethenyl homologues and benzothiazole derivatives, and evaluated their 5-lipoxygenase inhibitory activity in vitro with cell-free rat basophilic leukemia (RBL-1). In most cases the replacement of benzoxazolyl with benzothiazolyl resulted in an enhancement of the activity. All compounds with butadienyl spacers tested herein exhibited strong inhibitory activities. While most of the ethenyl homologues showed weaker activities than their corresponding butadienyl homologues, some ethenyl compounds in the benzothiazole derivatives were found to be as potent as their corresponding butadienyl homologues. The inhibitory activity was also affected by the variation in the p-hydroxyaryl functionality.

Animals↗
PubMed1997

Purification and characterization of dipeptidyl aminopeptidase from Aureobacterium sp. WO26.

We isolated a bacterial strain with an enzyme which releases dipeptide from Gly-Arg-p-nitroanilide. The bacterium was tentatively identified as Aureobacterium sp. The enzyme, named AuDAP, was purified and characterized. It was homogenous by SDS-PAGE and IEF, and had a molecular mass of 90,000 Da by SDS-PAGE and 88,000 Da by gel filtration, so it may be a monomer. The isoelectric point was 3.8 and the optimum pH was 10.0. The purified enzyme hydrolyzed Gly-Arg-pNA, a model substrate for DAP I, and Arg-Arg-MNA, a model substrate for DAP III. However, this enzyme did not hydrolyze Gly-Phe pNA, also a model substrate for DAP I. These results suggested that this enzyme did not fall under the classification of mammalian DAPs and was similar to DAP BI from Pseudomonas sp. WO24 and dDAP from Dictyostelium discoideum, although several differences were observed between them. The N-terminal amino acid sequence of this enzyme showed no significant homology to any enzyme and protein, except only for DAP BI.

Dipeptidyl-Peptidases and Tripeptidyl-Peptidases↗
PubMed1997

In vivo antitumor effect of cationic liposomes containing diphtheria toxin A-chain gene on cells infected with bovine leukemia virus.

A plasmid pLTR-DT which contained a gene for diphtheria toxin A-chain (DT-A) under the control of the long terminal repeat (LTR) of bovine leukemia virus (BLV) (BLV-LTR) in the multicloning site of pUC-18 was entrapped in cationic liposomes composed of N-(alpha-trimethylammonioacetyl)-didodecyl-D-glutamate chloride (TMAG), dioleoyl phosphatidylethanolamine (DOPE) and dilauroyl phosphatidylcholine (DLPC) (1:2:2, molar ratio) (TMAG-liposome), and their antitumor effect on BLV-infected tumor cells was examined in vivo. The cationic TMAG-liposome containing pLTR-DT was successively injected into the tumor transplanted to nude mice. The growth of tumor was significantly inhibited by the injection of cationic TMAG-liposome containing pLTR-DT. On the other hand, TMAG-liposome containing pUC18 plasmids showed no such effect. These results suggest that a DT-A expression plasmid under the control of BLV-LTR is highly toxic to the BLV-infected tumor cells, and that the cationic liposomes, such as TMAG-liposome, may be efficient transfection reagent for BLV-infected tumor cells and can be utilized for DT-A gene delivery into BLV-infected tumor cells in vivo.

Animals↗
PubMed1997

Lymphostin (LK6-A), a novel immunosuppressant from Streptomyces sp. KY11783: taxonomy of the producing organism, fermentation, isolation and biological activities.

In the course of screening for inhibitors of the lymphocyte kinase, Lck (p56lck), aiming at novel immunosuppressants, we isolated a novel alkaloid, lymphostin (LK6-A), from the culture broth of Streptomyces sp. KY11783. Lymphostin was produced in a fermentation medium supplemented with a highly porous polymer resin, which prevented the degradation of this compound in the culture broth. Lymphostin inhibited the kinase activity of Lck with an IC50 value of 0.05 microM, and exhibited potent inhibitory activity against the mixed lymphocyte reaction (MLR) with an IC50 value of 0.009 microM.

Chromatography, High Pressure Liquid↗
PubMed1997

GE3, a novel hexadepsipeptide antitumor antibiotic, produced by Streptomyces sp. I. Taxonomy, production, isolation, physico-chemical properties, and biological activities.

GE3, a novel cyclic hexadepsipeptide antibiotic, was isolated from the culture broth of Streptomyces sp. GE3. GE3 was weakly active against some Gram-positive and Gram-negative bacteria and showed potent cytotoxicity against human tumor cell lines. GE3 also exhibited antitumor activity against human pancreatic carcinoma, PSN-1, in vivo. GE3B, a linear peptide form of GE3, which was isolated from the same culture broth with GE3, showed no antibiotic and cytotoxic activities, suggesting the necessity of the cyclic structure of GE3 for its biological activities.

Animals↗
PubMed1997

[Influence of atrioventricular delay on pulmonary capillary wedge pressure in two patients with hypertrophic obstructive cardiomyopathy during dual chamber pacing].

Recently, dual chamber pacing has been proposed as a new treatment for left ventricular outflow tract obstruction in patients with hypertrophic obstructive cardiomyopathy (HOCM). However, dual chamber pacing may be detrimental to both systolic and diastolic function of the left ventricle, particularly at short atrioventricular (AV) delay. A 45-year-old man and a 58-year-old woman with HOCM underwent transesophageal echocardiography and hemodynamic study at various AV delays (50-200 msec). In both patients, shortening of AV delay increased pulmonary capillary wedge pressure. The transesophageal echocardiographic study showed a remarkable shortening of the ventricular filling duration at atrial systole and an increase of pulmonary venous reversal at short AV delay (50-100 msec). Therefore, short AV delay was detrimental to diastolic filling and thus increased pulmonary capillary wedge pressure. Transesophageal echocardiographic study may be helpful for defining the optimal AV delay more precisely in HOCM during dual chamber pacing.

Blood Flow Velocity↗
PubMed1997

[Myocardial wall motion analysis with phase shift imaging: cine phase contrast technique].

MR imaging can be used to measure proton velocity directly as a phase shift with the bipolar gradient method. This method is applied in MR angiography as a phase contrast(PC) technique. We attempted to evaluate myocardial motion utilizing the PC technique. With the cine PC technique, 16-cardiac phased 3D velocity images of the myocardium were obtained. In normal subjects, the myocardial velocity throughout the cardiac cycle were changes regular in space as well as in time, and there was no inconsistency between the motion directions. Whereas, in cases with myocardial infarction, 3D velocity images revealed some regions with zero velocity and/or some regions which showed reverse direction motions compared with the surrounding normal myocardium.

Heart↗
PubMed1996

Evaluation of three individual glucosyltransferases produced by Streptococcus mutans using monoclonal antibodies.

We previously established murine hybridomas producing a monoclonal antibody monospecific against three glucosyltransferases (I, SI and S) of Streptococcus mutans which contribute to dental caries formation. Here, we developed a new immunochemical technique (cross-dot system) with which individual levels of glucosyltransferases expressed by S. mutans can be evaluated. We also examined glucosyltransferase production and in vitro artificial plaque formation by a reference strain and several clinical isolates of S. mutans. The findings indicate that the levels of glucosyltransferases produced greatly vary with the cells and the culture medium, and that the cells producing high levels of both glucosyltransferase-SI and glucosyltransferase-I enzymes may possess high in vitro artificial plaque forming ability. We suggest that the cross-dot system will be useful for estimating the cariogenic potential of S. mutans isolates.

Antibodies, Monoclonal↗
PubMed1996

MS-271, a novel inhibitor of calmodulin-activated myosin light chain kinase from Streptomyces sp.--I. Isolation, structural determination and biological properties of MS-271.

A novel cyclic peptide, MS-271, was isolated from the culture broth of an actinomycete, Streptomyces sp. M-271 as an inhibitor of smooth muscle myosin light chain kinase (MLCK). MS-271 inhibited the MLCK from chicken gizzard with an IC50 value of 8 microM. MS-271 did not inhibit cyclic AMP-dependent protein kinase, protein kinase C or calcium/calmodulin-dependent cyclic nucleotide phosphodiesterase at concentrations up to 400 microM. The primary structure of MS-271 was identical to that of siamycin I, an anti-HIV peptide isolated from a microbial source.

Adenosine Triphosphate↗
PubMed1996

Inherited muscular disorder in mutant Japanese quail (Coturnix coturnix japonica): an immunohistochemical study.

Cryostat sections of myofibres from the Musculus pectoralis thoracicus of a newly established mutant strain (LWC) of Japanese quail with a myotonic dystrophy-like myopathy were labelled with antibody against myosin heavy chain (MHC) isoforms and neural cell adhesion molecule (N-CAM). The characteristic lesions found in sections of muscle of LWC quail stained with haematoxylin and eosin were type 2B fibre atrophy, sarcoplasmic masses, and ring fibres. Immunohistochemical examination failed to distinguish type 2A and 2B fibres in the LWC quail. Antibody to adult fast MHC, which reacted only with type 2A fibres in normal quail, reacted in LWC quail with type 2B fibres, and to a limited degree with type 2A fibres. Sarcoplasmic masses reacted with both fast and slow MHC antibodies. Some masses also reacted with NCAM antibody, but apparently independently of similar reactions in fibres. These findings suggest that the changes observed in the myofibres of the LWC quail were not neurogenic but represented defects in both the plasma membrane and intermediate filaments.

Animals↗
PubMed1996

Inherited muscular disorder in mutant Japanese quail (Coturnix coturnix japonica): an ultrastructural study.

Ultrastructural study of muscles taken from a mutant (LWC) strain of Japanese quail with myotonia showed type 2 fibre atrophy, ring fibre formation, sarcoplasmic masses, and "moth-eaten" fibres. In these abnormal fibres, the most characteristic feature was the loss of interconnection among the myofibrils, mitochondria, and T tubules. Apparently normal muscle fibres often showed mild changes, such as proliferation of T tubules and enlarged sarcoplasmic areas with increased glycogen granules and ribosomes at the periphery of the fibres. The study suggested that one possible cause of these ultrastructural changes was a defect in cytoskeleton of muscle cells, especially in intermediate filaments.

Animals↗
PubMed1996

Effect of estriol on bone loss in postmenopausal Japanese women: a multicenter prospective open study.

OBJECTIVES: To assess the effects of oral estriol on the bone mineral density (BMD) and bone metabolism in postmenopausal women. METHODS: Seventy-five natural postmenopausal women with a BMD of more than 10% below the peak bone density were treated for 50 weeks with 2 mg/day estriol (E3) cyclically and 0.8 g/day of calcium lactate continuously. BMDs at L2-L4 were measured by dual energy X-ray absorptiometry (DXA). RESULTS: The BMD increased 1.79% (p < 0.01 vs. pretreatment) after 50 weeks, accompanied with decrease of biochemical markers of bone turnover. With regard to climacteric symptoms, Kupperman's menopausal index improved (p < 0.01 vs. pretreatment) after 5 weeks of treatment. As to the incidence of adverse events genital bleeding was observed in only 8.0% of the subjects. Endometrial histology and cytology showed neither abnormalities nor hyperplasia during and after the treatment. CONCLUSIONS: Estriol prevented postmenopausal bone loss and improved climacteric symptoms effectively with low incidence of genital bleeding.

Bone Density↗
PubMed1996

Detection of Novel Proline 3-Hydroxylase Activities in Streptomyces and Bacillus spp. by Regio- and Stereospecific Hydroxylation of l-Proline.

During the screening of microbial proline hydroxylases, novel proline 3-hydroxylase activities, which hydroxylate free l-proline to free cis-3-hydroxy-l-proline, were detected in whole cells of Streptomyces sp. strain TH1 and Bacillus sp. strains TH2 and TH3 from 3,000 strains isolated from soil. The reaction product was purified from a reaction mixture of Streptomyces sp. strain TH1, and its chemical structure was identified as cis-3-hydroxy-l-proline by instrumental analyses. Proline 3-hydroxylase activity was also detected in Streptomyces canus ATCC 12647 which produces the 3-hydroxyproline-containing peptide antibiotic telomycin. Bacillus sp. strains TH2 and TH3 were found to accumulate cis-3-hydroxy-l-proline in culture media at 426 and 352 (mu)M, respectively. It was suggested that hydroxylation occurred in a highly regio- and stereospecific manner at position 3 of l-proline because no hydroxylation product other than cis-3-hydroxy-l-proline was observed. Proline 3-hydroxylases of these strains were first characterized on crude enzyme preparations. Since 2-oxoglutarate and ferrous ion were required for hydroxylation of l-proline, these 3-hydroxylases were thought to belong to a family of 2-oxoglutarate-related dioxygenases. The reaction was inhibited by Co(sup2+), Zn(sup2+), and Cu(sup2+). l-Ascorbic acid accelerated the reaction. The optimum pH and temperature were 7.5 and 35(deg)C, respectively.

Journal Article↗
PubMed1996

Immunosuppressive factor from Actinobacillus actinomycetemcomitans down regulates cytokine production.

A cytoplasmic soluble fraction of Actinobacillus actinomycetemcomitans Y4 was isolated and characterized as suppressing mitogen-stimulated proliferation of and cytokine production by C3H/HeN mouse splenic T cells. This factor, designated suppressive factor 1 (SF1), was isolated from the supernatant of sonicated whole bacteria and purified by Q-Sepharose Fast Flow column chromatography, DEAE-Sepharose Fast Flow column chromatography, hydroxyapatite high-pressure liquid chromatography (HPLC), and Protein Pack 300 & 125 gel filtration HPLC. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that the purified SF1 migrated as a single band corresponding to a molecular mass of 14 kDa. This molecule was protease labile, heat resistant, and noncytotoxic. N'-terminal sequence analysis revealed no homology with any known peptides of periodontopathic bacteria or with any host-derived growth factors. Purified SF1 suppressed the proliferation of mouse splenic T cells which had been stimulated with concanavalin A, as well as suppressing the production of interleukin-2 (IL-2), gamma interferon, IL-4, and IL-5 from CD4+ T cells as 0.1 microgram/ml or more. These data suggest that SF1 produced by the periodontal pathogen A. actinomycetemcomitans functions as a virulence factor by down regulating T-cell proliferation and cytokine production at local defense sites.

Aggregatibacter actinomycetemcomitans↗