The use of Herr four-and-a-half clearing fluid for the rapid microscopic examination of thick sections of normal and neoplastic tissues.

We have demonstrated that Herr's 4 1/2 clearing fluid, developed for use with plant tissues, can be successfully used for the microscopic examination of thick sections of normal and neoplastic mammalian tissues. Rat Novikoff hepatoma, rat liver, and human colon and skin samples were fixed in Bouin's, stained with iron hematoxylin, treated with Herr's 4 1/2 clearing fluid and examined by phase contrast microscopy. Tissue architecture and cytological detail were easily observed by focusing through tissue sections as thick as 70 mu. The method permits rapid microscopic examination of mammalian tissues and enables the investigator to detect readily morphological abnormalities within a tissue.     

Synthesis of protoporphyrin IX induced by 5-aminolevulinic acid in yeast cells in the presence of 2,2;-dipyridyl

5-Aminolevulinic acid (ALA), a precursor of porphyrin synthesis, increased the production of various porphyrin compounds in Candida guilliermondii cells. Metalloporphyrins and protoporphyrin IX (PPIX) were predominantly accumulated, respectively, at ALA concentrations of 0.2-0.4 mM and at those higher than 1.5 mM. 2,2;-Dipyridyl which complexed with bivalent metals significantly increased the content of endogenous PPIX even at ALA concentrations lower than 0.5 mM. Under these conditions, the yeast sensitivity to photodynamic effect of visible light (400-600 nm) dramatically increased due to photosensitization by endogenous PPIX.     

The influence of analogs of xanthine on the mutagenic effect of ultraviolet light

Summary Eight compounds can be added to those purine analogs which give synergistic effects with ultraviolet light: 1,3,7,9-tetra-methylxanthine methyl sulfate, 8-chlorocaffeine, ethyltheophylline, 6-dimethylaminopurine, 6-methoxypurine, 8-ethoxycaffeine, 1,3-dimethyl uric acid and 3-methyl uric acid. It appears likely that these are merely representatives of the class of methyl purines, and that other compounds are also active. The synergistic activity varies among the compounds investigated; some give a synergistic effect slightly higher than caffeine, but apparently act by the same mechanism. The height of effect of all of the synergistic purine analogs has been correlated with the stability of the structures determined by inductive effects and steric hindrance. The lack of activity with pyrimidines (l-methyl thymine and 1,3-dimethyluracil) leads to the conclusion that both rings (7,8,9 positions) of the purine molecule are necessary for the synergistic effect.This work was supported by the National Institutes of Health Research Grant AI-05340, the University of Kansas General Research Fund, and an N.I.H. Training Grant (5 T1 GM-703) to the Department of Microbiology.     

The Use of Herr Four-and-a-Half Clearing Fluid for the Rapid Microscopic Examination of Thick Sections of Normal and Neoplastic Tissues

We have demonstrated that Herr's 4¹/₂ clearing fluid, developed for use with plant tissues, can be successfully used for the microscopic examination of thick sections of normal and neoplastic mammalian tissues. Rat Novikoff hepatoma, rat liver, and human colon and skin samples were fixed in Bouin's, stained with iron hematoxylm, treated with Herr's 4¹/₂ clearing fluid and examined by phase contrast miaoscopy. Tissue architecture and cytological detail were easily observed by focusing through tissue Sections as thick as 70μ. The method permits rapid microscopic examination of mammalian tissues and enables the investigator to detect readily morphological abnormalities within a tissue.