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Biomedical subjects

S Natori

Publications and source records attributed to S Natori.

At least 361 records · Page 20Linked to original sources
PubMed1978

Acute toxic effects of chaetoglobosin A, a new cytochalasan compound produced by Chaetomium globosum, on mice and rats.

A new cytochalasan compound, chaetoglobosin A produced by Chaetomium globosum, was studied for its toxicity to animals. By subcutaneous injection, 2 mg/kg body weight of chaetoglobosin A killed young Wistar rats acutely, and in the mouse of DDD strain, LD50 values of chaetoglobosin A were estimated 6.5 and 17.8 mg/kg for male and female, respectively. By oral administration, 400 mg/kg of chaetoglobosin A caused little adverse effect on mice and rats. Pathological examination of the mice, injected subcutaneously with 5 mg/kg of the toxin, revealed marked edema at the injection site which appeared in several hours after injection and subsided in a week. In other tissues necrosis of the thymus and spleen and degeneration of the spermatocytes in the testicles were noticeable. With characteristic cytotoxic effects like cytochalasin B, chaetoglobosin A is an interesting mycotoxin, although it may be of little significance as a food- or feed-borne toxin.

Animals↗
PubMed1978

Toxic effects of rice culture of Aspergillus candidus and its metabolite, xanthoascin, on Japanese quails.

Laying Japanese quails were fed on diet of 1:1 mixture of basal diet and rice cultures of 2 strains of Aspergillus candidus. During 20 days of feeding, egg production was significantly reduced in these groups compared with the birds fed unmolded rice. The liver of the quails sacrificed at 20 days showed fatty degeneration of hepatic cells. Following withdrawal of the moldy rice, rate of egg production recovered in 5 days. The suppressive effect of egg production seems to be secondary to hepatic injury. In the other experiment, xanthoascin, a purified mycotoxin of A. candidus, was given subcutaneously between 2 to 5 mg/g body weight. In all groups mortality was about 80%. Survivors produced no eggs 10 days following the injection. The liver of quails that died in 1 to 4 days showed focal necrosis, fine droplet fatty degeneration and bile thrombosis of bile ductules. The features are similar to those observed previously in mice and rats, but the quail is far more sensitive to injected xanthoascin than rodents.

Animals↗
PubMed1977

Protein which interacts with a stimulatory factor of RNA polymerase II of Ehrlich ascites tumor cells.

When partially purified Ehrlich ascites tumor RNA polymerase II was further purified on a column of phosphocellulose, stimulation of its catalysis of RNA synthesis by stimulatory factor S-II was greatly decreased. This decrease in sensitivity to the stimulatory factor was reversible: the enzyme eluted from phosphocellulose became sensitive to the factor when mixed with a protein fraction eluted from the phosphocellulose at high salt concentration. Evidence was obtained that this protein, named helper protein, binds, to the enzyme eluted from phosphocellulose, causing it to recover sensitivity to stimulatory factor S-II.

Animals↗
PubMed1977

Accumulation of immunoglobulin messenger ribonucleic acid in immunized mouse spleen.

We have measured the concentration of mRNAs coding for immunoglobulins, k and lambda type light chains and gamma 1 type heavy chain, in mouse spleen cells activated by bacterial lipopolysaccharide or sheep red blood cells. These mRNAs were quantitated by hybridization to radioactive DNA complementary to highly purified immunoglobulin mRNAs from mouse myelomas. In the lipopolysaccharide-stimulated spleen cells, only light chain mRNA accumulated, whereas gamma 1 type heavy chain mRNA remained unvaried. The light chain mRNA concentration also increased in purified bone-marrow-derived lymphocytes. The lipopolysaccharide-induced light chain mRNA was similar to light chain mRNAs purified from myelomas. The accumulation and disappearance of light chain mRNA in bone-marrow-derived lymphocytes coincide with the kinetics of synthesis of immunoglobulin M which is the major species induced by lipopolysaccharide. In sheep red blood cell stimulated spleen, the specific accumulation of k type light chain and gamma 1 type heavy chain mRNAs parallels immunoglobulin G synthesis. These results seem to indicate that the increment of immunoglobulin mRNA concentration in bone-marrow-derived lymphocytes is important for induction of immunoglobulin synthesis.

Animals↗
PubMed1977

Bacterial lipopolysaccharide induction of a mouse spleen factor stimulating ribonucleic acid polymerase II.

When bacterial lipopolysaccharide, a B-cell mitogen, was injected intraperitoneally into mice, the rate of deoxyribonucleic acid synthesis and the number of antibody-secreting cells in the spleen increased simultaneously, reaching a maximum in 3 days. The rate of ribonucleic acid synthesis also increased during this period, and this was found to be due to activation of alpha-amanitin-sensitive transcription in lymphoid cells of the spleen. The factors stimulating ribonucleic acid polymerase II in the spleens of normal mice and those treated with lipopolysaccharide were compared, and an additional factor besides that present in normal spleens was found in the spleen of lipopolysaccharide-treated mice.

Animals↗
PubMed1976

Purification of a factor from Ehrlich ascites tumor cells specifically stimulating RNA polymerase II.

A factor stimulating RNA polymerase II from Ehrlich ascites tumor cells was purified. The final preparation appeared almost homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and had a molecular weight of 38 000. The endonuclease activity of about 10 mug of purified factor, if any was well below the 10(-5) mug equivalent of pancreatic deoxyribonuclease, indicating that the stimulation of RNA synthesis by this factor was not due to contaminating endonuclease. This factor specifically stimulated RNA polymerase II on native DNA as template and did not affect RNA polymerase I at all. The molecular size of RNA synthesized in the presence of this factor increased markedly compared with that synthetized by RNA polymerase II alone.

Animals↗
PubMed1975

DNA dependent RNA polymerase from Ehrlich ascites tumor cells. V. Characterization of a factor repressing RNA polymerase II as a ribonucleoprotein.

Previously we reported the isolation of a factor, named the R-protein, which strongly repressed RNA polymerase II [EC 2.7.7.6] of Ehrlich ascites tumor cells. In the present work this factor was found to contain much RNA (ratio of RNA to protein, 2.3 to 1). The RNA was G:C rich, with a very high content of guanylic acid (about 38%). On equilibrium density gradient centrifugation in Cs2SO4 solution, the RNA became distributed above free RNA, but after digestion of the R-protein with pronase the RNA cosedimented with free RNA. Thus the R-protein is a complex of RNA and protein.

Animals↗