Saburo Yamashita

Studies on iodinated compounds : V. Reversed-phase high-performance liquid chromatographic determination of iodide with cyclodextrin-containing mobile phases

Abstract α-,β-,/gg- and dimethyl-β-cyclodextrin (CD) were used as mobile phase additives in a reversed-phase high-performance liquid chromatographic determination of iodide (I−). The retention of I− was decreased by the addition of CDs in mobile phases composed of hexyl-, heptyl- or octylammonium phosphate. The decrease in the retention was influenced by the molecular species and the concentration of CDs. Using 2 mM heptylammonium phosphate (pH 4.0) containing 2 mM β-CD as the mobile phase, determination of I− was performed with a UV detector at 226 nm. Good linearity of the calibration graphs and good reproducibility of repeated determinations were obtained for I− in the range 25 pmol (3.2 ng) to 12.5 nmol (1.6 μg).

Variation of increases in free cytosolic calcium ion induced by prostaglandin E2 in mouse osteoblast clone, MC3T3-E1—Single cell assay using microspectro-fluorometry

Osteoblasts exhibit multiple phenotypic expression in response to prostaglandin E2 (PGE2). Intracellular calcium concentration ([Ca2+]i) was elevated by PGE2 treatment in the mouse osteoblast clone, MC3T3-E1, but the degree of elevation was varied by the day after subculturing. To study the different response to PGE2, we have used microspectrofluorometry to measure [Ca2+]i in a single MC3T3-E1 cell loaded with fura-2. In the presence of extracellular Ca2+, the increase in [Ca2+]i in the osteoblast exhibited multiple patterns. The patterns were roughly classified into four groups by the time reached maximum level; “transient”, “gradual”, “transient and gradual” and “no response”. Within 2 days after subculturing, the cells showing “gradual” and “no response” were predominant, whereas after day 3 the cells showing “transient” and “transient and gradual” were predominant. We also investigated the daily change in the maximum level of [Ca2+]i in the cells showed “transient” in response to PGE2. The magnitude of [Ca2+]i increase was also varied in cultivating period. These data suggest that there are phenotypic variations in a single cell even in a cloned cell line and this phenotype may change in the stage of cell proliferation.

Studies on iodinated compounds : VI. Separation characteristics of iodohistidines on reversed-phase high-performance liquid chromatography

Abstract The separation of iodohistidines [monoiodohistidine (MIH) and diiodohistidine (DIH)] by reversed-phase high-performance liquid chromatography on octade-cylsilylsilica columns was attempted in comparison with the separation of iodotyrosines. The retention of iodohistidines with the phosphate buffer used as the mobile phase was relatively small, and less pH dependent. However, the retention increased with the addition of hydrophobic ion-pairing agents to the mobile phase. When acetic acid was used in the mobile phase, DIH was eluted by reversed-phase elution, MIH by polar-phase elution. The separation of iodohistidines was largely dependent on the properties of the stationary phase, silanophilic interactions being influential. It may be concluded that the separation of iodohistidines will be best accomplished when an high ionic strength, low pH mobile phase containing an alkanesulphonate is used.

Changes of lysosomal enzyme activities in experimental type I and type IV allergic models

Experimental allergy was induced in animals: asthma, a Type I allergy, was induced in guinea pigs by sensitizing them with alpha-amylase (inhalation), and experimental allergic encephalomyelitis (EAE), a Type IV allergy, was induced in rats. Pulmonary, brain and serum lysosomal enzyme activities were measured in normal and allergic conditions. beta-Glucuronidase (beta-G) and arylsulfatase (AS) activities were determined by the fluorescent technique. During the asthmatic attack, pulmonary lysosomal enzyme activities were not different from that in the normal state in guinea pigs. However, brain lysosomal enzyme activities were elevated markedly on the 1 st day of EAE induction. Brain beta-G activity was elevated on the 2nd day, and AS activity had a tendency to be increased. On the other hand, serum lysosomal enzyme activity was not altered significantly. In the experimental allergy, lysosomal enzyme activity was altered in Type IV, but not in Type I.

Comparative Studies on Lactase Preparations

Comparisons of enzymatic activities of five commercial lactase preparations were made in terms of the sensory tests of such properties as appearance, smell and taste.β-Galactosidase activities were different among preparations, and the activity was found to be higher or lower than the labelled activity of the respective preparations. Stability of the enzyme activity at various temperatures and pH was also different among preparations. Marcked characteristics of other enzymes contained were also shown in the potency test and sensory test.