Rikuro Sasaki

Generation of free radicals and initiation of radical reactions in nitrones — Fe2+ - phosphate buffer systems

Abstract Stability of spin trapping reagents, phenyl-tert-butylnitrone (PBN) and 5,5-dimethyl-pyrroline-N-oxide (DMPO), in Fe2+-phosphate buffer (pH 7.8 and 7.0) was examined. Both nitrones generate the spin adducts without substrate. It was supposed that PBN and DMPO produce the benzoyl and hydroxyl spin adducts, respectively, by the decomposition of themselves in the system. The presence of alcohols causes the initiation of radical reaction and leads to strong ESR signals due to hydroxyalkyl spin adducts.

Effects of Aging on Hydroxyproline in Human Heart Muscle

Hydroxyproline concentration in the NaCl‐soluble, TCA‐soluble, and residual fractions of heart muscle was chemically determined in 40 autopsy subjects (25 men and 15 women), to study the effects of aging. In the left ventricle, the total hydroxyproline content of the endocardium and papillary muscle increased significantly in relation to age; the increase was greatest in the TCA‐soluble fraction, followed by the residual fraction. Statistical analysis revealed that hydroxyproline in the residual fraction increased from the epicardium to the endocardium and then to the papillary muscle. Significant negative correlations were found between heart weight and total hydroxyproline in the epicardium and endocardium. In the right ventricle, a significant negative correlation was noted between heart weight and total hydroxyproline content. Though no correlations were evident between age and hydroxyproline content in females, significant correlations were observed between age and the total hydroxyproline content of the endocardium and papillary muscle in males. Furthermore, soluble collagen increased in most parts of the heart in females, but insoluble collagen increased in all parts of the heart in males. It is concluded that the hydroxyproline content of heart muscle increases in proportion to age and is in inverse proportion to heart weight. The increase occurs in the TCA‐soluble and residual fractions, and extends from the endocardium to the papillary muscle. More profound changes in collagen metabolism are observed in males.

Biochemical examination on the increased superoxide dismutase-like plasma substance observed in a state of acute gastric mucosal lesions

When experimental acute gastric mucosal lesions were produced in guinea pig by water-immersion and restraint stress, superoxide dismutase (SOD)-like substance in the plasma increased. On analysis by gel filtration, it was shown that the molecular weight of the increased SOD-like plasma substance was about 130,000, and even after treatment with trypsin, 84% of this substance remained. Since the molecular weight of intracellular SOD is about 40,000, it seems that this substance is similar to extracellular SOD, located on the endothelial cell-surface, as previously reported by Marklund et al. Our results suggest that in the presence of acute gastric mucosal lesions, SOD-like plasma substance is not identical to intracellular SOD, which derived from cell destruction by stress or free radical-induced microvascular damage or by hemolysis. Furthermore, this substance may itself work as a scavenger of free radicals generated under conditions, such as these described in the present experiment.

Stomach Cancer in Various Age Groups (Japan) As Detected by Gastric Mass Survey

ABSTRACT: In order to determine the characteristics of stomach cancer in the elderly, statistical analyses were made of 2,366 cases found in a gastric mass survey (group 1) and 194 cases found among 9.196 persons over age 40 observed during 13 years (group 2). For group 1, the average annual incidence of stomach cancer per 100,000 persons by age, and the death rate by age, increased as age advanced. The average annual incidence was 0.19 percent over 18 years and there were almost no changes in the detection rate. For group 2, the death rate per 10,000 persons in the examined group was significantly lower than in the non‐examined group, especially for persons in their 50s or 60s. However, there were no differences in the death rate for persons in their 40s, 70s, and beyond. The rate for surgical resection of cancer and the incidence of early stomach cancer were lower in the elderly; the 5‐year relative survival rate was poor. Thus, the clinical characteristics of stomach cancer in the elderly include the following aspects: 1) in mass surveys, the incidence of stomach cancer is highest in the elderly, especially for men; 2) many cases of stomach cancer are advanced or inoperable; and 3) most of these patients do not undergo examination until they become aware of symptoms related to cancer.