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Biomedical subjects

M Izawa

Publications and source records attributed to M Izawa.

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

Dynamics of glucocorticoid receptor and induction of tyrosine aminotransferase in rat liver.

In order to better understand the role of glucocorticoid receptor in the hormonal action of glucocorticoid, depletion and replenishment of the cytoplasmic receptor and kinetics of induction of tyrosine aminotransferase (TAT) in rat liver were examined after administration of dexamethasone (Dex) and prednisolone. The extent of the receptor depletion and the duration of the depletion period were dose-dependent and were well correlated not only with the biological potency of the steroids administered but also with the kinetics of TAT induction. A linear relationship between the amount of depleted receptor and the kinetics of TAT induction was observed. Pretreatment of animals with a large dose of Dex reduced the response of TAT induction by Dex which was administered 24 h later. This seems to be attributable, at least in part, to the incomplete replenishment of the receptor and also to the increased rate of replenishment of the receptor. The reduced affinity of the partially replenished receptor to glucocorticoid might also participate in lowering the response to the second injection. In conclusion, depletion and replenishment of the cytoplasmic glucocorticoid receptor appeared to be directly responsible for the physiological action of glucocorticoid.

Animals↗
PubMed1982

[A case of huge calcified chronic subdural hematoma].

In the literature, there has been no report of spontaneously growing calcified chronic subdural hematoma (C-C-SDH). The authors report a five-year-old boy with spontaneously growing C-C-SDH. The patient was admitted to author's department on July 24, 1979, because of progressive right hemiparesis, seizure and mental as well as physical retardation. He had a birth injury caused by forceps delivery resulting in skull fracture and subarachnoid hemorrhage. Three months after birth, gradual enlargement of his head circumference was noticed. A ventriculoperitoneal shunt was performed under the diagnosis of acute hydrocephalus. At the age of 17 months, he developed meningitis followed by right hemiparesis. When he was three years old, bilateral C-SDH was found on CT. The irrigation of hematoma was not successful because of the organization of hematoma. At the age of 4, calcification of the hematoma was found on CT and plain skull x-rays. Because of deterioration of the right hemiparesis, seizure and the enlargement of C-SDH, he was admitted to author's department on July 24, 1979. The left C-SDH was totally removed on August 10, 1979 by craniotomy. The extirpated C-C-SDH was 15 X 10 cm and 2 cm in thickness. Both inner and outer capsule were thick. The organized and partially calcified tissue was found between the two capsules. Sinusoidal blood vessels were also identified on the inner and outer capsules. Postoperatively, hemiparesis became improved. The second operation to the right C-C-SDH was performed from one year later after the first craniotomy. Surgical indication of C-C-SDH has to be determined on the basis of patient's age, symptoms and length of clinical course. It has been suggested that surgical treatment of C-C-SDH in children was not successful as compared with that in adults. The authors emphasize that C-C-SDH in children should be operated to encourage mental and physical development of the patients as well as to prevent hemorrhage and growth of C-C-SDH.

Calcinosis↗
PubMed1981

Poly(ADP-ribose) synthesis in nucleoli and ADP-ribosylation of nucleolar proteins in mouse ascites tumor cells in vitro.

Poly(ADP-ribose) synthetic activity in isolated nucleoli from rapidly growing mouse ascites tumor cells and ADP-ribosylation of the nucleolar proteins in vitro were studied. The specific activity of the synthesis in the nucleoli was significantly higher than that in the chromatin. The optimum magnesium and NAD+ concentrations, and the effect of RNase treatment on the reaction in the nucleoli were also distinctly different from those in the chromatin. Hydrolysis of the reaction product of the nucleoli with snake venom phosphodiesterase and with calf thymus poly(ADP-ribose) glycohydrolase yielded 5'-AMP and 2'-(5"-phosphoribosyl))5'-AMP, and ADP-ribose, respectively. The average chain length of the polymer formed in the nucleoli was found to be about 4 as a whole, but the distribution was heterogenous, from 1.2 to over 12. Analysis of ADP-ribosylated proteins in the nucleoli by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed that several non-histone proteins with molecular weights of over 100,000 were highly ADP-ribosylated compared with other proteins including histones. This pattern was also different from that of the chromatin. These experimental results demonstrate that the nucleoli are independent from the chromatin as regards poly(ADP-ribose) synthesis in vitro.

Adenosine Diphosphate Ribose↗
PubMed1981

Microbial conversion of ansamitocin.

Bacteria, actinomycetes, yeasts, and fungi were screened for their ability to modify the structure of ansamitocins, a group of antitumor ansamycin antibiotics. Many strains, mostly actinomycetes, were found to convert ansamitocin P-3 to one or more products. These products, compounds A, B, C, and D, were prepared using Bacillus megaterium IFO 12108, Streptomyces coelicolor IFO 3807, Streptomyces castaneus IFO 13670 and Streptomyces minutiscleroticus IFO 13361, and were identified as 20-O-demethylansamitocin P-3, maytansinol, 15-hydroxyansamitocin P-3 and N-demethylansamitocin P-3, respectively. Other maytansinoids also underwent these microbial conversions.

Bacteria↗
PubMed1981

Ansamitocin analogs from a mutant strain of Nocardia. I. Isolation of the mutant, fermentation and antimicrobial properties.

A mutant having a high ability to produce ansamitocins was derived from a dnacin-producing strain, Nocardia sp. No. C-14482 (N-1001), by treatment with ethidium bromide. Mutant N-1231 produced ansamitocins P-3 and P-4 as major components, but was deficient in its ability to produce dnacins. Strain N-1231 also produced fifteen novel ansamitocin analogs as minor components. These analogs showed no activity against prokaryotic micro-organisms. The results of determining the activity inhibiting cilia regeneration of deciliated Tetrahymena pyriformis suggest that hydroxylation of C15, C26 and the acyl moiety at C3 of ansamitocins may cause marked reduction of their antitubulinic activities whereas demethylation of -NCH3 at C18 slightly affected their activities.

Anti-Bacterial Agents↗
PubMed1981

[The effects of fosfomycin on antigenicity (author's transl)].

The antigenicity of fosfomycin (FOM), a new antibiotic agent, was studied. The binding of 3H-FOM with human serum protein was measured by the short term dialysis method. The binding was very weak only by 2.16% and reversible. The rabbits were immunized subcutaneously by fosfomycin as sodium salt (FOM-Na) with FREUND'S complete adjuvant. Antigenicity of IgG was examined by means of agar gel precipitation, passive cutaneous anaphylaxis and passive hemagglutination. To study the antigenicity of IgE, the BALB/cA mice were immunized intraperitoneally by FOM-Na with aluminum hydroxide gel and, passive cutaneous IgG and IgE. Consequently, it can be concluded that FOM does not conjugate with human serum protein to form its hapten and has not antigenicity.

Animals↗
PubMed1981

[A case of cerebrovascular Moyamoya disease associated with basilar aneurysm (author's transl)].

A case of Moyamoya disease associated with a basilar aneurysm was reported. The patient was a 49-year-old male who was attacked by subarachnoid hemorrhage in February 1980. Upon admission to our hospital, he was in good general condition and neurological examinations showed mild left hemiparesis and meningeal irritation signs. Four-vessel angiography showed bilateral stenosis and occlusion of the internal carotid arteries and abnormal vascular network in the cerebral base. Another conspicuous angiographic finding was a berry aneurysm associated with a daughter aneurysm at th basilar top. Enhancement CT scan revealed the basilar aneurysm and a well demarcated low density area in the right parietal lobe. It has generally been thought that the cause of symptoms in Moyamoya disease is rupture of vessels in the subarachnoid space on the cerebral cortex. However, in the case of Moyamoya disease associated with an aneurysm, rupture of the aneurysm should be considered to be a probable cause of subarachnoid hemorrhage.

Arterial Occlusive Diseases↗
PubMed1980

Interaction of 3H-dexamethasone-receptor complex with nuclei: inhibition by Ethidium Bromide.

Several binding characteristics of the Dexamethasone (DEX)-receptor complex(RC) to nuclei from rat tissues were examined in the presence of Ethidium Bromide(EB). In the cell-free experiments, EB partially prevented the binding of the liver DEX-RC to nuclei and two kinds of nuclear binding of the DEX-RC, one was sensitive and the other was resistant to EB, were observed. In addition, the EB-resistant nuclear binding that showed a high-affinity and low-capacity nature was observed only in the bindings of the 3H-DEX-RC to nuclei derived from the liver of fetal and adult rats and the thymus of adult rats. The bindings of 3H-5 alpha-Dihydrotestosterone(DHT)-RC and 3H-17 beta-Estradiol(E2)-RC to liver nuclei exhibited low-affinity and non-saturation even in the presence of EB. Furthermore, it was revealed, that the EB-resistant sites of the nuclear binding were for the "DNA-unbound" form of 3H-DEX-RC, while the RC of "DNA-bound" form was bound to the EB-sensitive sites.

Animals↗