Takeshi Muraki

Histochemical staining of cadmium with benzothiazolylazonaphthol derivatives

SummaryAs part of the continuous developmental research for a highly sensitive chelating agent for cadmium, benzothiazolylazophenol derivatives (BTAP) were synthesized and their staining properties for cadmium were examined. The compounds synthesized for this study were identified as being BTAP by analysis of their melting points and C,H,N,S content. Benzothiazolylazo-p-methoxyphenol,-p-chlorophenol and -p-cresol stained cadmium with the highest optical density and the most precise localization amongst dyestuffs reported to date. Differential sequestration by pyrophosphate makes it possible to distinguish cadmium masked by the presence of zinc. With the modification of a chelating agent to increase sensitivity, the improvement in molar absorptivity was also considered theoretically.

Histochemical staining of cadmium with 2-(8-quinolylazo)-4,5-diphenylimidazole

In order to develop a stain with increased sensitivity and selectivity for cadmium (Cd), we synthesized and characterized 2-(8-quinolylazo)-4,5-diphenylimidazole (QAI). This chelating agent was more than twice as sensitive for Cd than the best conventional staining agents, including benzothiazolylazo-beta-naphthol. Differentiation between Cd and zinc (Zn) was achieved by immersing tissue sections in TRIS(2-aminoethyl)amine before they were stained with QAI. This pretreatment made it possible to selectively stain for Cd by blocking Zn.

The choice of a masking agent in the histochemical staining of metals.

SummaryThe masking effects of standard masking agents (aminopolycarboxylic acids, carboxylic acids and phosphates) have been investigated in both test-tube experiments and tissue sections in order to ascertain the factors which must be considered when choosing a masking agent for the histochemical staining of a metal. The masking effectsin vitro were determined by spectrophotometry through the complexing of the dye Chrome Azurol S with aluminium, beryllium, and iron at pH 5 and 7. The effects were also examined by staining metal-containing tissue sections in a Chrome Azurol S masking agent system at the same pH values. In many cases, the masking effects observed in sections did not agree with those obtained in the test-tube experiments. This means that the published values of stability constants are not a sufficient guide for choosing a suitable masking agent for the staining of metals. The discrepancy is mainly attributable to the presence of protein in a solid state when metals are stained in sections. Therefore, in the future, consideration should be given to a metal-protein or masking agent-protein interaction using a model compound such as a chelate resin. The polyphosphates are among the most useful masking agents for metal staining in acidic solutions from a practical standpoint.

Histochemical staining of exogenous chromium and iron with the catalytic oxidation of phenylamines

SummaryA highly sensitive and specific method for staining exogenous chromium and iron in tissues is described. This method is superior to conventional complex-forming methods with regard to its sensitivity and specificity for these metals. The staining reaction is based on the metalcatalysed oxidation of phenylamines. Tissue sections were incubated in a medium containing hydrogen peroxide and phenylamines, p-phenylenediamine or phenylhydrazine. Results obtained from test-tube experiments concerning the catalytic activities of metals indicated that the staining reactions depends on the activities of metals in tissues.

The staining properties of pyridylazophenol analogs in histochemical staining of a metal.

SummaryThe compound 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(Br-PADAP) was found capable of staining very small amounts of metals in tissue. This finding stemmed from the examination of the staining properties of pyridylazophenol analogs; 2-(2-pyridylazo)-phenol, 2-(2-pyridylazo)-5-dimethylaminophenol, 1-(2-pyridylazo)-2-naphthol, 4-(2-pyridylazo)-resorcinol, and Br-PADAP. The unusually high sensitivity of Br-PADAP is attributed to the presence of an alkylamino group at the 5-position of the benzene ring. The presence of this alkylamino group forms a charged quinoid structure, and contributes resonance and optimum solubility to the hybrid by introducing a bromine atom into the pyridine ring. We report the staining results obtained from a variety of metals and the molar absorptivity of their metal chelates.

A morphologic study of the behavior of biogenic amines in experimental acetic acid gastric ulcer.

SummaryMorphological observations were made of the behavior of biogenic amines in the gastric wall of rats with acetic acid-induced ulcer. In the normal rat stomach, abundant adrenergic fibers were seen in the adventitia of arteries and arterioles, with frequently distributed mast cells in their environs, in all gastric wall layers. Mast cells had a more frequent distribution in the antral region than in the corpus ventriculi while enterochromaffin-like cells (EC-like cells) were found with greater frequencies in the latter region of gastric wall. Adrenergic fibers were abundant around blood vessels in perilesional area of the gastric wall of rats with acetic acid ulcer. Mast cells, seen more frequently in the antral region as in the normal rats, showed degranulation in these rats. The population of PAS-positive mucous cells reached its peak in 10 days after injection of acetic acid and subsequently declined with healing of the ulcer, thus remarkably concordant with the ulcer index. Local administration of serotonin produced angiospasm in the greater omentum. The finding indicates a possible participation of arteriospasm by adrenergic nerve fibers in the pathogenesis of gastric ulcer. The results of the present study strongly suggest that biogenic amines have bearing as an aggressive factor upon the angiospasm theory of ulcerogenesis.