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Biomedical subjects

Y Nishimoto

Publications and source records attributed to Y Nishimoto.

At least 145 records · Page 8Linked to original sources
PubMed1982

Formation of Crystalline delta-Endotoxin or Poly-beta-Hydroxybutyric Acid Granules by Asporogenous Mutants of Bacillus thuringiensis.

Parental strains and asporogenous mutants of Bacillus thuringiensis subspp. kurstaki and aizawai produced high yields of delta-endotoxin on M medium, which contained 330 mug of potassium per ml, but not on ST and ST-a media, each of which contained only 11 mug of potassium per ml. On ST and ST-a media, refractile granules were formed instead. These granules had no insecticidal activity against silkworms and were isolated and identified as poly-beta-hydroxybutyric acid. Supplementation of the potassium-deficient ST-a medium with 0.1% KH(2)PO(4) (3.7 mM) led to the formation of crystalline delta-endotoxin. The replacement of KH(2)PO(4) with equimolar amounts of KCl, KNO(3), and potassium acetate or an equivalent amount of K(2)SO(4) had a similar effect, whereas the addition of an equimolar amount of NaH(2)PO(4) or NH(4)H(2)PO(4) did not cause the endotoxin to form. An asporogenous mutant, B. thuringiensis subsp. kurstaki strain 290-1, produced delta-endotoxin on ST-a medium supplemented with 3 mM or more potassium but formed only poly-beta-hydroxybutyric acid granules on the media containing </=1 mM potassium. These results clearly indicate that a certain concentration of potassium is essential for the fermentative production of delta-endotoxin by these isolates of B. thuringiensis. Manganese could not be substituted for potassium. Phosphate ions stimulated poly-beta-hydroxybutyric acid formation by strain 290-1. The sporulation of B. thuringiensis and several other Bacillus strains was suppressed on the potassium-deficient ST medium. This suggests that potassium plays an essential role not only in Bacillus cell growth and delta-endotoxin formation but also in sporulation.

Journal Article↗
PubMed1982

Asporogenous Bacillus thuringiensis Mutant Producing High Yields of delta-Endotoxin.

An asporogenous Bacillus thuringiensis subsp. kurstaki strain IK mutant, strain 290-1, which produced high yields of delta-endotoxin, was obtained by ethyl methane sulfonate treatment of a spore suspension. The mutant strain produced about the same amount of delta-endotoxin as that produced by the parent strain, but 10 to 10 cells did not form any detectable dormant spores.

Journal Article↗
PubMed1982

A preferential isolation procedure for asporogenous Gram-positive bacteria.

A preferential isolation procedure was devised for asporogenous (Asp), Gram-positive (Gp), aerobic or facultative anaerobic bacteria which included the genera Arthrobacter, Corynebacterium, Brevibacterium, Microbacterium, Mycobacterium, and Micrococcus (Asp-Gp bacteria). An antibiotics-mixture agar which contained 5 to 10 micrograms per ml of colistin, 10 to 20 micrograms per ml of nalidixic acid and 30 micrograms per ml of cycloheximide was used in the isolation. Using this technique 47 Asp-Gp bacteria representing 26 subgroups of coryneform bacteria and Micrococcus were isolated from 3 soil samples. The method was far more efficient than the standard dilution-plate technique. This preferential method is available to isolate Asp-Gp bacteria from a sample containing about 500-fold more of other Gram-positive and negative bacteria.

Bacteria↗
PubMed1982

A selective isolation procedure for Micromonospora.

A selective medium containing 25 to 50 micrograms per ml of tunicamycin was devised to isolate micromonosporae from soil samples, making possible simple, preferential isolation of a variety of Micromonospora. When a large amount of Gram-negative bacteria was present in a sample, alkaline treatment (0.01 N NaOH, 5 approximately 10 minutes at 15 degrees C) wa employed to reduce the numbers. Using the tunicamycin agar medium, 1,585 strains of presumably different micromonosporae were obtained from 400 soil samples collected from various regions around the world. In average, 4 different Micromonospora strains could be located from one soil sample. This tunicamycin method made possible a concentrated screening method for new antibiotics from Micromonospora.

Bacteria↗
PubMed1982

[Amyl nitrite test in the evaluation of left ventricular function: application to ischemic heart disease and Duchenne's progressive muscular dystrophy].

The effect of amyl nitrite (AN) inhalation on the left ventricular function was evaluated by mechanocardiography and echocardiography. The patient's group consisted of 110 cases with ischemic heart disease (IHD) and 25 cases of dystrophia musculorum progressiva (DMP) of Duchenne type. The former was a representative of impairment of blood supply and myocardial involvement, and the latter was of predominant myocardial disease. The control was age-matched 32 normals for IHD group and 17 cases for DMP group. Left ventricular function was mainly evaluated by systolic time intervals (STI) and the echocardiographic correlates. Fifty-five cases of IHD group were tested by coronary angiography and left ventriculography and these data were compared with the noninvasive measures. The results were as follows: I. IHD group: The ratio of ejection time (ET) to pre-ejection period (PEP), ET/PEP, did not change so much as in controls after AN inhalation, and this percent change was much smaller in cases with lesions of the left anterior descending artery (LAD) than in cases with lesions of the right coronary artery (RCA). On the other hand, mean posterior wall velocity (mPWV) and posterior wall excursion (PWE) changed greater in patients with LAD lesion than in those with RCA lesion. In cases with LAD stenosis, percent change in ET/PEP was smaller in cases with asynergy than in cases without it, disclosing more significant impairment of the left ventricle in the former. II. DMP group: In severe cases, ET/PEP was small even at rest, and percent change by AN inhalation was smaller than control in mild cases and smallest in severe cases. This seems to be useful in evaluating the severity of the diseased process. The mPWV and PWE showed impairment of left ventricular motion even at rest, but it was clearly showed in severe cases after AN inhalation. These results indicate that impairment of left ventricular function induces the poor response to AN inhalation and this, in turn, results in the lack of hyperactivity of the heart produced by this drug.

Adolescent↗
PubMed1981

[Effect of hyperthermia and methylprednisolone acetate on circulating thrombocytes in mice].

The effect of microwave-induced whole body hyperthermia and methylprednisolone acetate on the count of circulating thrombocyte in mice was investigated. Mice were heated at 43.5 degree C for 5, 10, 15 or 45 minutes with or without anesthesia. In all cases a high level of thrombocytosis was induced. Such effect was abolished by administration of methylprednisolone acetate 3 hours before heat treatment.

Animals↗
PubMed1981

Effects of hyperthermia on cell surface charge and cell survival in mastocytoma cells.

Changes in the structure of the surface of mastocytoma cells were induced by hyperthermia and were investigated by means of cell electrophoresis. A decrease in the cell electrophoretic mobility was detected as early as 15 min after treatment at 42 degrees and progressed more rapidly under hypoxic conditions than under oxic conditions. Subsequent recovery of electrophoretic mobility at 37 degrees was dependent on the length of heat treatment and oxygenation. The surviving fraction of cells detected by their colony-forming ability and the fraction of electrophoretically recovered cells 24 hr after exposure to hyperthermia showed a good statistical correlation. It was suggested that the mechanism of electrophoretic mobility reduction by heating was the vertical translocation of hyaluronidase-sensitive charge from the peripheral layer into a deeper layer by combined use of specific enzymes and stepwise different ionic strengths. These results suggest the importance of irreparable changes of membrane conformation in the loss of colony-forming ability of heated tumor cells.

Animals↗