Hiroshi Ohkawa

Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction

The reaction of lipid peroxides in animal tissues with thiobarbituric acid was dependent on pH of the reaction mixture as was the case for linoleic acid hydroperoxide. The optimum pH was found to be 3.5. Taking this fact into consideration, a standard procedure for the assay of lipid peroxide level in animal tissues by their reaction with thiobarbituric acid was developed as follows. Ten percent (wv tissue homogenate was mixed with sodium dodecyl sulfate, acetate buffer (pH 3.5), and aqueous solution of thiobarbituric acid. After heating at 95°C for 60 min, the red pigment produced was extracted with n-butanol-pyridine mixture and estimated by the absorbance at 532nm. As an external standard, tetramethoxy-propane was used, and lipid peroxide level was expressed in terms of nmol malondialdehyde. Using this method, the liped peroxide level in the liver of rats suffering from carbon tetrachloride intoxication was investigated. The results were in good agreement with previously reported data obtained by measuring diene content.

SUPPRESSION BY TRANILAST OF FETAL MYOSIN HEAVY CHAINS AND INTIMAL HYPERPLASIA IN RABBITS

Abstract Percutaneous transluminal angioplasty is commonly used in patients with vascular stenosis. However, after this procedure, there is a high rate of restenosis, which is thought to result from intimal hyperplasia. Tranilast ( N -3,4-dimethoxycinnamoyl anthranilic acid) has been found to decrease intimal hyperplasia. This study investigated the appearance of myosin heavy chain (MHC) isoforms during healing after vascular endothelial injury in rabbits. It also determined the effect of tranilast on this process and the resultant intimal hyperplasia. Ten adult male rabbits were divided into two equal groups after each animal received infrarenal aortic endothelial injury by means of a balloon catheter. One group received tranilast (500 mg/kg per day) for 14 days; the other group did not receive any drug and served as controls. After 14 days all rabbits were killed. Sections of the injured aorta were studied microscopically for the degree of intimal hyperplasia and immunohistologically using the streptavidin-biotin method with anti-MHC isoform SM1, SM2, and SMemb primary antibodies. Measurements were made in a masked fashion by one author. Both groups showed anti-SM1—positive and anti-SMemb—positive cells in the neointima. In the tranilast group, the SM1 and SMemb counts were significantly lower than in the control group. The neointima area was significantly smaller in the tranilast group than in the control group. Similarly, the neointima to media ratio was significantly lower in the tranilast group than in the control group. Tranilast appears to inhibit the fetal MHC and thus reduce intimal hyperplasia.

Structure and Function of Cema Homologue (PXCA) in Cyanobacteria

The cemA (ycf10) gene codes for a chloroplast envelope membrane protein [1] and is conserved in higher and lower plants and in algae [2–8]. CemA in higher plants consists of 229 to 231 amino-acids [2–4] whereas that in liverwort (Marchantia) [5] and Chlamydomonas [6] is much larger and consists of 434 and 500 amino-acids, respectively. Recent sequencing of whole chloroplast genomes of Porphyra [7] and Chlorella [8] revealed that cemA in these algae encodes proteins of 278 and 264 amino-acids, respectively. The function of CemA is not known. Rolland et al [6] have constructed mutants by disrupting cemA in Chlamydomonas. They showed that the disruption of the gene led to increased light sensitivity and affected CO2-dependent photosynthesis and inorganic carbon uptake.