Hisayuki Tanizawa

Effect of Adriamycin on the Activities of Superoxide Dismutase, Glutathione Peroxidase and Catalase in Tissues of Mice

The increment of lipid peroxide in the hearts of mice treated with adriamycin (ADR) was examined in relation to the decrease in the activities of Superoxide dismutase (SOD), glutathione peroxidase (GSHpx) and catalase. The natural activities of these enzymes in mouse heart are lower than those in the liver. The biggest decrease in enzyme activity observed in the heart after ADR administration was that of GSHpx. Therefore, the increment of lipid peroxide was attributable to the decrease in the activities of these enzymes, especially GSHpx. Subsequently, the effects of antioxidants on the decreases in activities of SOD, GSHpx and catalase in the hearts of mice treated with ADR were examined. However, the decrease in the activities of the enzymes were not accompanied with any increment of lipid peroxide. This result suggests that active oxygen radicals produced by ADR through the agents redox cycling have no effect on the activities of these enzymes. Therefore, it appears that the decrease in the activities of these enzymes induced by ADR in the mouse results from inhibition of enzyme protein biosynthesis.

Phenylethanoid glycosides from Plantago asiatica

Abstract Six new phenylethanoid glycosides, plantainosides A–F, were isolated from a water extract of the whole plants of Plantago asiatica together with eight known phenylethanoid glycosides. Their structures were determined on the basis of chemical and spectral evidence.

Neuronal and vascular pathology produced by verocytotoxin 2 in the rabbit central nervous system.

Abstract To study the pathogenesis of the central nervous system (CNS) involvement associated with verocytotoxin-producing Escherichia coli infection, we developed an animal model by administering verocytotoxin 2 to rabbits either intravenously or intrathecally. After an interval of 2–9 days, the rabbits became paralyzed in a dose-dependent manner and in the absence of renal impairment. The minimal intravenous and intrathecal doses that produced these neurological signs were 250 and 0.4 ng/kg, respectively. After intravenous administration, most of the toxin was cleared from the serum within 24 h, with concomitant transition of a small amount into the cerebrospinal fluid. Pathological examination revealed that neurons in various CNS regions showed atrophy, cytoplasmic hyperchromasia and nuclear pyknosis as early as 6 h after administration. The distribution of affected neurons was constant and irrespective of the route of administration. Abnormalities of the blood vessels, such as the thickening of arterioles walls, were noted from 2 days after administration. The vascular lesions became more prominent after the intrathecal injection, which caused thrombosis and multiple infarction. Selective deposition of the toxin on the vessel walls was demonstrated immunohistochemically. Thus, the pathological manifestations of verocytotoxin 2 neurotoxicity consisted essentially of two types of lesions, early neuronal and late vascular, both of which might have developed under the influence of the toxin that had entered the CNS by crossing or circumventing the blood-brain barrier.

Effect of Adriamycin on DNA, RNA and Protein Biosyntheses in Mouse Tissues, in Connection with Its Cardiotoxicity

We examined whether the cause of the remarkable decreases in the activities of lipid peroxidationpreventive enzymes in the heart of adriamycin (ADR)‐treated mice might be related to inhibition of DNA, RNA or protein biosynthesis. It was found that biosyntheses of DNA, RNA and protein in the heart, liver and kidney of mice were markedly inhibited by ADR (15 mg/kg, ip). The inhibitory effects of ADR on each type of biosynthesis were particularly marked in the heart among the tissues examined. Strong correlations between the percentage inhibition of DNA and protein biosynthesis by ADR, and the percentage decrease in the activities of lipid peroxidationpreventive enzymes were observed in the heart, liver, kidney and lung, especially for the decrease of glutathione peroxidase activity and the inhibition of DNA and protein biosyntheses. We also found that marked decreases of DNA, RNA and protein biosyntheses in ADR‐treated mice occurred not only in the heart but also in tumor tissues. From these results, we conclude that the increment of cardiac lipid peroxide in ADR‐treated mice, which is closely related to the cardiotoxicity of ADR, results from inhibition of DNA, RNA and protein biosyntheses after the distribution of ADR.

ESR Imaging on a Solid-tumor-bearing Mouse Using Spin-labeled Dextran

Imaging of a tumor with ESR was tried using two different types of spin probes, a low molecular weight spin probe, CPROXYL, and a polymer spin probe, TEMPO-DX. Spin probes were administered to a mouse bearing a solid tumor that was a transplanted Ehrlich’s ascites carcinoma in the back, using two methods, conventional intraperitoneal injection and continuous intravenous injection with a micro-feeder. First, the accumulation of the probe was examined by X-band ESR. CPROXYL, which was administered to a mouse intraperitoneally, was exclusively retained in urine, showing that it was rapidly excreted into the bladder, while TEMPO-DX was absorbed from the peritoneal cavity with difficulty to the vessel. Using continuous intravenous injection, CPROXYL was also rapidly excreted, but it was confirmed that TEMPO-DX concentrated in tumor tissue because it has a long half-life in vivo. In addition, measurement of ESR imaging was done to measure the distribution of spin probes with continuous intravenous injection. The strongest spot of CPROXYL was observed on ESR images, showing the accumulation at the bladder, while the spot of TEMPO-DX was observed in the solid tumor of the back of the mouse. These results suggest that TEMPO-DX could stay much longer than a low molecular weight spin probe in vivo and concentrate at the tumor. TEMPO-DX may be useful for developing specific ESR imaging agents for tumor.

Sulfated N-Myristoyl Chitosan as a Surface Modifier of Liposomes

Sulfated N-myristoyl chitosan (S-M-chitosan), which is strongly electrolytic and water soluble as well as partly hydrophobic due to long alkyl chains, was synthesized to be used as a liposome-surface modifier. The effects of the treatment with an aqueous S-M-chitosan solution on the stability of the liposome suspension prepared from hydrogenated egg yolk lecithin were examined on several points. A suspension of large liposomes prepared by the Bangham method was precipitated by standing for a day, but the precipitation was restrained when the sample was treated with S-M-chitosan solution. The turbidity of a small liposome suspension was changed greatly after the suspension was freeze-thawed, but the change was small in the treated sample. A similar result was obtained when the suspension was freeze-dried following the addition of water. These results come from the facts that the surface of the liposome was coated with S-M-chitosan and negatively charged as ascertained by the measurement of zeta potential and the electron microscopic observation. The repulsive force between charges was considered to be the origin of the stabilization. It was also shown from an ESR experiment that the treatment suppressed the elution rate of the material incorporated into the liposomes.