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K Toyooka

Publications and source records attributed to K Toyooka.

52 records · Page 3Linked to original sources
PubMed1990

Effect of 2,4-dihydro-3H-1,2,4-triazole-3-thiones and thiosemicarbazones on iodide uptake by the mouse thyroid: the relationship between their structure and anti-thyroid activity.

Antithyroid activity of 2,4-dihydro-3H-1,2,4-triazole-3-thiones and thiosemicarbazones was tested by measuring the uptake ratio of thyroid: serum (T/S) of 125I through the mouse thyroid. Substitution with an alkyl group at the 5-position of the triazole nucleus remarkably increased the activity but substitution at the N-2 and/or N-4 positions caused a significant decrease in the activity, indicating the necessity of unsubstituted thioureylene moiety for the antithyroid activity. Thiosemicarbazone derivatives which are an open ring structure of triazoles showed comparable antithyroid activities to those in a ring form, but one thiosemicarbazone showed a much higher toxicity than the corresponding ring form compound. This suggests that the ring structure is not essential for the activity but is necessary to reduce toxic effect. Of fourteen compounds tested, 5-methyl-2,4-dihydro-3H-1,2,4-triazole-3-thione was the most potent antithyroid compound with low toxicity, with a potency tenfold that of propylthiouracil, a drug currently used.

Animals↗
PubMed1989

Ethylidene glucose-substituted new analogue of streptozotocin cannot induce diabetes: study on the basis of structure and activity relationship.

4,6-O-Ethylidene glucose (ethylidene glucose), a specific inhibitor at the outer surface of a glucose transporter in the cell membranes, substituted analogue of streptozotocin was newly synthesized. This compound did not induce diabetes in rats and also did not show cytotoxic effect on pancreatic beta cells of neonatal rats in a monolayer culture system. The reasons why such a molecule was designed and why it showed no biological effects are discussed on the basis of a structure-activity relationship. Our results afford positive evidence for the presence of a glucose transport system or a glucose transporter on pancreatic beta cells and its involvement in the action of streptozotocin on beta cells.

Animals↗
PubMed1987

Protective effect of 4,6-O-ethylidene glucose against the cytotoxicity of streptozotocin in pancreatic beta cells in vivo: indirect evidence for the presence of a glucose transporter in beta cells.

Ethylidene glucose (4,6-O-ethylidene glucose; EG) is known to bind the outer surface of the glucose transporter in the membranes of human erythrocytes and other mammalian cells. If a glucose transport system is present on pancreatic beta cells and recognizes the glucose moiety of streptozotocin (STZ), EG should protect beta cells from the cytotoxicity of STZ when it is administered with STZ. This possibility was examined in in-vivo experiments in rats. When EG and STZ were injected into rats together the animals did not become diabetic, as judged by their blood glucose levels, response in a glucose-tolerance test, and insulin secretion in response to feeding. These results suggest that there is a glucose transporter present in beta cells and also the transport of streptozotocin into beta cells through this system.

Animals↗
PubMed1982

Synthesis and structure--activity relationship of nonyl 3-acyldithiocarbazates and related compounds for uncoupling activities.

Various nonyl 3-substituted-dithiocarbazates, methyl and dimethyl derivatives of nonyl 3-benzoyldithiocarbazate, nonyl 2-substituted-dithiocarbamates, and benzaldehyde nonyldithiocarbohydrazone were synthesized and their uncoupling activities of oxidative phosphorylation in mitochondria were examined. The results indicate that the presence of the thiocarbamoyl structure with the potential SH group is a requisite for uncoupling activity. The presence of a C=O group and a hydrophobic aromatic ring significantly increases the uncoupling activity.

Animals↗
PubMedDate not supplied

[Intravascular malignant lymphomatosis: an autopsy case with generalized telangiectasia and various neurological manifestations].

We report a 73-year-old woman with intravascular malignant lymphomatosis (IML) who showed generalized telangiectasia as well as various neurological symptoms. In July 1998, she developed fever, dizziness, and confusion followed by left hemiparesis, and was admitted to our hospital on August 11, 1998. Laboratory tests indicated a normochromic normocytic anemia, thrombocytopenia, elevated serum lactic dehydrogenase (LDH), C-reactive protein (CRP), and cerebrospinal fluid protein. Magnetic resonance imaging (MRI) of the brain revealed an infarct-like lesion in the left frontal lobe and multiple white matter lesions. After admission, her neurological status deteriorated and lapsed into coma and quadriplegia. At the end of September 1998, generalized telangiectasia appeared, and she was diagnosed as IML on skin biopsy. Although combination chemotherapy failed to improve her neurological symptoms, telangiectasia disappeared in a few days, and the infarct-like lesion on MRI decreased in size. Serum LDH, CRP, and thrombocyte counts were normalized. Autopsy findings revealed perivascular clustering of B cell type lymphoma cells in the left frontal lobe where abnormal signal intensity was found on MRI, as well as the spleen and the bone marrow. This case emphasizes the importance of early diagnosis and treatment in IML.

Aged↗