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T Koga

Publications and source records attributed to T Koga.

At least 595 records · Page 33Linked to original sources
PubMed1986

Purification and characterisation of the extracellular D-glucosyltransferase from serotype c Streptococcus mutans.

A simple method of purification for the extracellular D-glucosyltransferase (GTase) from a serotype c strain Streptococcus mutans was developed using chromatography on DEAE-Sephacel and CM-cellulose. The GTase had a molecular weight of 155,000 and an isoelectric point of 7.4. The enzyme converted sucrose, in the absence of dextran T-10, into a branched (1----6)-linked alpha-D-glucan having some alpha-(1----3)-linked D-glucosyl residues. The GTase was similar to GTases which have been isolated from other strains of serotype c S. mutans and which synthesise water-soluble glucans. In addition, the amino acid composition of the GTase protein was relatively similar to those of the GTases from serotype g S. mutans which synthesise water-soluble and water-insoluble glucans.

Amino Acids↗
PubMed1986

Origin of intracellular calcium and quantitation of mobilizable calcium in neutrophils stimulated with chemotactic peptide.

The origin and amount of mobilized Ca2+ in chemotactic peptide-stimulated guinea pig neutrophils were examined using biochemical techniques. The total amount of releasable Ca2+ by 20 microM A23187 from the unstimulated intact cells was 0.91 nmol/4 X 10(6) cells, as assessed by change in absorbance of the antipyrylazo III-Ca2+ complex. Two types of internal vesicular Ca2+ pool, mitochondrial and non-mitochondrial pool were identified in the saponin-permeabilized cells. The total amount of releasable Ca2+ was comparable to that accumulated by the non-mitochondrial pool at (1-2) X 10(-7) M of a free Ca2+ concentration. The mitochondrial uncoupler, capable of releasing Ca2+ from the mitochondrial pool, neither modified the basal cytosolic free Ca2+ in quin 2-loaded cells nor caused a Ca2+ efflux from the intact cells. These results suggest that the releasable Ca2+ may be located in the non-mitochondrial pool of unstimulated intact cells, and the mitochondrial pool contains little releasable Ca2+. The addition of fMet-Leu-Phe increased the cytosolic free Ca2+ by two processes: Ca2+ mobilization from internal stores and Ca2+ influx through the surface membrane. The Ca2+ mobilized and effluxed from the intact cells by stimulation with the maximal doses of fMet-Leu-Phe was estimated to be 0.27 nmol/4 X 10(6) cells. Almost equal amounts were released by the maximal doses of inositol 1,4,5-trisphosphate from the non-mitochondrial pool of saponin-treated cells that had accumulated Ca2+ at a free Ca2+ concentration of 1.4 X 10(-7) M. The mechanism related to the Ca2+ influx by fMet-Leu-Phe stimulation was also examined. The addition of nifedipine or phosphatidic acid did not affect the change in the cytosolic free Ca2+ induced by fMet-Leu-Phe, thereby suggesting that the receptor-mediated Ca2+ channel may be involved in the Ca2+ influx.

Animals↗
PubMed1986

Guanine nucleotide binding protein involved in muscarinic responses in the pig coronary artery is insensitive to islet-activating protein.

In an attempt to identify the nature of guanine nucleotide binding protein(s) (G-protein) involved in the acetylcholine (ACh)-induced (muscarinic) response of pig coronary-artery smooth muscle, we studied the effect of ADP-ribosylation of specific membrane protein(s) catalysed by islet-activating protein (IAP; pertussis toxin). The ACh-stimulated and guanine nucleotide-dependent activities of phosphatidylinositol 4,5-bisphosphate (PIP2) phosphodiesterase (PDE), assessed by the production of inositol 1,4,5-trisphosphate (IP3) from exogenously applied PIP2, were not modified, in either IAP-treated or non-treated cell homogenates used as the enzyme source. In intact tissues, pretreatment with up to 100 ng of IAP/ml inhibited neither the ACh-induced decrease in the amount of inositol phospholipids nor the increase in the amounts of phosphatidic acid and of inositol phosphates. IAP treatment increased the amount of cyclic AMP accumulated by isoprenaline. These observations suggest that G-protein which couples the muscarinic receptor to PIP2-PDE is insensitive to IAP. Such being the case, the nature of this protein(s) probably differs from that required for the regulation of adenylate cyclase activities (Ni or Gi).

Acetylcholine↗
PubMed1986

Human recombinant interleukin 1-mediated suppression of glycosaminoglycan synthesis in cultured rat costal chondrocytes.

Effects of human recombinant interleukin 1 (IL-1) on the synthesis of glycosaminoglycan were examined with cultured rat costal chondrocytes. Incorporation of [35S]sulfate into glycosaminoglycan was strikingly diminished by the addition of IL-1 in a dose- and time- dependent manner. When the cells were cultured with 340 micrograms/ml of IL-1 for 72 hr, the synthesis of glycosaminoglycan was inhibited to 10% of the control. On the other hand, IL-1 had no effect on the morphology and proliferation of the chondrocytes. The suppression of glycosaminoglycan synthesis remained unchanged after the addition of indomethacin, indicating that the effect of IL-1 is independent of the enhanced synthesis of prostaglandins.

Animals↗
PubMed1986

Requirement of Ca2+ for the production and degradation of inositol 1,4,5-trisphosphate in macrophages.

The requirement of Ca2+ for the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdInsP2) or the accumulation of inositol 1,4,5-trisphosphate (InsP3) in macrophages stimulated with fMet-Leu-Phe was examined using [32P]Pi or [3H]inositol-labeled cells. The dependence on Ca2+ of inositol-trisphosphate phosphatase was also examined. The application of 1 X 10(-8) M fMet-Leu-Phe caused a rapid decrease in the amount of PtdInsP2 to 70% of the control within 10 s, and the decrease was reverted to the control level by prolonged incubation. The decrease in the amount of PtdInsP2 accompanied the accumulation of phosphatidic acid and of InsP3, indicating that the loss of PtdInsP2 is due to phosphodiesteric breakdown. The dose-dependence of fMet-Leu-Phe or its analog on the hydrolysis of PtdInsP2 was much the same as that of the increase in intracellular free Ca2+ concentration in macrophages. The loss of PtdInsP2 as induced by fMet-Leu-Phe was similarly observed in macrophages treated with ionophore A23187 in the absence of external Ca2+ for 10 min. InsP3 was degraded by the particulate or cytosol fraction prepared from macrophages, and the activity of inositol-trisphosphate phosphatase in the particulate fraction was higher than that in the cytosol fraction. The enzyme in the cytosol fraction required Mg2+ for activity, and was activated by free Ca2+ concentrations ranging from 10(-7) to 10(-6) M in the presence of 1 mM MgCl2.

Animals↗
PubMed1986

Macrophage Ia expression in athymic nude versus neonatally thymectomized mice.

The requirement of the thymus for the production of Ia-inducing lymphokine was studied in athymic nude, neonatally thymectomized (NTx), and sham-operated (Sham) mice. The peritoneal macrophages from NTx mice immunized with viable Listeria monocytogenes 14 days previously contained as high a proportion of Ia-bearing macrophages as those from Sham mice, while those from athymic nude mice contained only a small proportion. Intraperitoneal injection of a culture supernatant derived from immune spleen cells of NTx mice induced Ia-rich exudates in recipient normal mice just as well as did a corresponding supernatant from cells of Sham mice, but that from cells of athymic nude did not. The production of Ia-inducing lymphokine in culture supernatants of immune spleen cells from both NTx and Sham mice was abolished by pretreatment of cells with anti-Thy-1.2 antibody plus complement. These results suggest that a T cell subset responsible for the production of Ia-inducing lymphokine requires the presence of the thymus for just a short period in the ontogenic development.

Animals↗
PubMed1986

Sucrose-dependent cell adherence and cariogenicity of serotype c Streptococcus mutans.

Four strains of serotype c Streptococcus mutans differing in glucosyltransferase (GTase) and fructosyltransferase (FTase) activities were examined. These strains had been made resistant to streptomycin. FTase activity of an S. mutans clinical variant, MT6801R, which forms large mucoid colonies on sucrose-containing agar, was considerably higher than that of a typical serotype c strain, MT8148R, which forms small, rough colonies on the same agar. Two mutants, NG14 and NG7183, were induced from strain MT6801R by N-methyl-N'-nitro-N-nitrosoguanidine, and were found to be streptomycin-resistant. GTase and FTase activities of mutant NG14 were similar to those of the typical serotype c strain, while in mutant NG7183 the two enzyme activities were very low. Growing cells of these strains (except NG7183) adhered firmly to a glass surface in sucrose broth. Resting cells of all strains attached in small numbers to saliva-coated hydroxyapatite in the absence of sucrose. On the other hand, the presence of sucrose markedly enhanced the attachment of cells of strains MT8148R, MT6801R and NG14, but not NG7183. Cell-surface hydrophobicity and acid production of all strains were similar. Both strain MT8148R and NG14 colonized tooth surfaces and produced significant dental caries in specific-pathogen-free rats. Strain MT6801R had lower colonization ability and cariogenicity when compared with strains MT8148R and NG14. Furthermore, mutant NG7183 was able to colonize the tooth surfaces in small numbers, but failed to cause dental caries. These results indicate that sucrose-dependent cell adherence mediated by de novo glucan synthesis is necessary for the accumulation of serotype c S. mutans cells on the tooth surface and the induction of dental caries.

Adsorption↗
PubMed1986

Purification and immunochemical properties of a protein antigen from serotype g Streptococcus mutans.

A proteinaceous antigen (PAg) was purified from the culture supernatant of Streptococcus mutans 6715 (serotype g) by ultrafiltration, ammonium sulfate precipitation, DEAE-Sephacel ion-exchange chromatography, Phenyl-Sepharose CL-4B hydrophobic chromatography, and subsequent Sephacryl S-300 gel filtration. A yield of 0.1 mg of PAg was obtained from a liter of culture supernatant. The isoelectric point and molecular weight of PAg were pH 4.6 and 210,000, respectively. It contained 35% sugar, which was identified as glucose by gas-liquid chromatography. Amino acid analysis revealed that PAg contains 28% acidic and 11% basic amino acid residues. PAg retained its antigenicity after heating at 80 C for 10 min in deionized water, or after treatment with 0.1 M HC1 or 0.1 M NaOH at 37 C for 1 hr. Immunodiffusion and immunoelectrophoresis analyses revealed that PAg is serologically distinct from other cell-surface antigens such as serotype-specific polysaccharide and lipoteichoic acid. A cross-reaction between PAg and a protein antigen similarly prepared from serotype c S. mutans was observed in immunodiffusion tests.

Amino Acids↗
PubMed1986

Composition of major outer membrane proteins of Vibrio vulnificus isolates: effect of different growth media and iron deficiency.

The outer membrane proteins of Vibrio vulnificus including isolates from humans, seawater and an asari clam were examined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. A major outer membrane protein with an apparent molecular weight of 48,000 (48K protein) was common to all the strains grown in 3% NaCl-nutrient broth; however this 48K protein was not produced in any of the strains grown in chemically defined medium. Other major outer membrane proteins with molecular weights ranging from 33,000 to 40,000 varied in number, relative amount and molecular weight depending on the strain. One to three new outer membrane proteins with molecular weights ranging from 74,000 to 85,000 were produced in the cells grown in iron-deficient medium. The 48K protein and one or two major proteins with molecular weights ranging from 35,000 to 37,000 in the cells grown in 3% NaCl-nutrient broth were not solubilized by 2% SDS at 60 C for 30 min and were resistant to trypsin, indicating that they are porins. On the other hand, in cells grown in chemically defined medium, one or two major outer membrane proteins with molecular weights ranging from 33,000 to 40,000 might be porins.

Bacterial Outer Membrane Proteins↗
PubMed1986

Muramyl dipeptide induces acute joint inflammation in the mouse.

Acute joint inflammation was produced in BALB/c mice by a single intravenous injection of synthetic muramyl dipeptide (MDP), its stereoisomers and 6-O-acyl derivatives of MDP. Four adjuvant-active, but not five adjuvant-inactive MDP analogs induced acute swelling and erythema of the ankles and wrists which were detected around 6-10 hr, reached the maximum severity by 18-24 hr and subsided by days 3 to 4 after injection. Introduction of the stearoyl group, but not the alpha-branched long chain fatty acid group into the C-9 hydroxyl group of MDP enhanced and prolonged the joint lesions compared with MDP.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1986

Augmentation of host defense by a unicellular green alga, Chlorella vulgaris, to Escherichia coli infection.

Protection against Escherichia coli inoculated intraperitoneally into mice was enhanced by intraperitoneal, intravenous, or subcutaneous administration of a water-soluble, high-molecular-weight fraction extracted from a dialyzed hot-water extract from a strain of Chlorella vulgaris (CVE-A). The enhancing effect was detected with doses over 2.0 mg/kg and when doses were administered 1, 4, or 7 days before the infection. The elimination of bacteria from the spleen of CVE-A-treated mice was increased, and this enhanced elimination may have been related to the acceleration of superoxide generation and chemokinesis in polymorphonuclear leucocytes by CVE-A treatment. A cyclophosphamide-induced decrease in protection against E. coli could be prevented by subcutaneous administration of CVE-A.

Animals↗
PubMed1986

[Studies on the occupational maladjustment syndrome. (Part 3). In reference to the therapeutic system for the OMA syndrome and the industrial physician's roles].

In order to ascertain the effects of the newly-devised therapeutic system (described later) and clarify the industrial doctor's roles, a study was made on 96 patients with O.M.A.S. (34 in core group, 26 in dropout group, 15 in other group, 13 in transient reaction group and 8 in special job maladjustment group) whom we had directly treated. The subjects of the present study were 54 patients with O.M.A.S. who were treated in the clinic (our clinic) at the Dept. of Mental Health, Osaka Prefectural Institute of Public Health during the past 19 years and 42 patients who were examined in the company's clinic (this company consists of 15,000 employees) where we have practiced mental hygiene of industrial medicine during the past 15 years. Two typical cases in respect of the therapeutic system are presented. We developed a newly-devised therapeutic system of O.M.A.S. (I. Medical examination, II. Counselling for the patients and their family, III. Psychiatric rehabilitation, and IV. Therapeutic advices for their colleagues or superiors in their working place). Of the 96 patients, 81 were reinstated to their office and are at work by using the therapeutic system. Of 96 patients it was necessary for 59 to accept the therapeutic advices. In 49 of 59 patients (Accepted group), doctor's therapeutic advices were accepted by their colleagues or superiors in their working place. In the remaining 10 patients (Refused group) treated by our clinic, the therapeutic advices were refused. Accepted group was observed to be more adaptable to their jobs than refused group. As to the therapeutic content we manipulated their conditions as follows: therapeutic transposition in 27 patients, reduction of duty and guidance of work in 18 patients, and therapeutic preliminary reappointment in 13 patients. It is considered that the industrial doctor of mental hygiene plays an important role in order to establish the therapeutic system of O.M.A.S.

Adaptation, Psychological↗
PubMed1986

[The simultaneous evaluation of serum NSE as a tumor marker in lung cancer compared with serum CEA--high sensitivity and specificity defined in the TP-FP curve].

Serum NSE and serum CEA levels were simultaneously examined in 40 patients with primary lung cancer and in 70 other patients without cancer, including 45 young healthy subjects, 13 cases of chronic obstructive pulmonary diseases (COPD), and 12 cases of pulmonary tuberculosis. The primary lung cancers consisted of 13 small cell carcinomas, 12 adenocarcinomas, 11 epidermoid carcinomas, 3 large cell carcinomas, and 1 unclassified. The mean serum NSE level in the 40 primary lung cancer cases was 18.4 +/- 65.7 ng/ml, the levels for small cell carcinomas, adenocarcinomas, epidermoid carcinomas, and large cell carcinomas being 46.8 +/- 46.7 ng/ml, 3.8 +/- 1.0 ng/ml, 4.6 +/- 2.8 ng/ml and 3.6 +/- 0.3 ng/ml, respectively. The levels in young healthy subjects, COPD cases, and pulmonary tuberculosis cases were 3.0 +/- 0.59 ng/ml, 3.2 +/- 0.51 ng/ml and 5.0 +/- 1.5 ng/ml, respectively. In order to evaluate the efficacy of NSE as a tumor marker, we calculated the true positive ratios and false positive ratios for serum NSE, as on indicator of sensitivity and specificity. It was concluded that serum NSE is an excellent new tumor marker compared with CEA, especially for small cell carcinomas.

Adenocarcinoma↗