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Recently we reported that feline and canine dental calculus fluoresced pink to red under long wavelength ultraviolet light due to the presence of porphyrin. Here we report the observation of such fluorescence in 30 of 30 cats, 30 of 30 dogs, and 8 of 13 supragingival samples and 5 of 5 subgingival samples of humans. The fluorescence spectra of the calculus dissolved in 9 M HCl show that it is due to three distinct metal-free porphyrins. Similar fluorescence is obtained from bacterial cultures grown from calculus deposits of cats and dogs and bacteria grown on blood agar containing hemin and vitamin K1. The results of the bacterial culture study suggest that the metal-free porphyrin is produced by bacteria in the mouth. The clinical observation of fluorescence can be used for diagnosis.

This study has demonstrated the feasibility of determining erythrocyte protoporphyrin concentration by the direct fluorimetric measurement of diluted whole blood. Excitation and emission wavelengths can be chosen to minimize heme (or hemoglobin) interference. Although results obtained by this method and an extraction method differed, the discrepancies were approximately constant and largely explainable on a basis of fluorescence quenching by heme. Nevertheless, several kinds of pathologic blood specimens having elevated protoporphyrin concentrations were easily detectable. Perhaps more important from a diagnostic sense, the method can be used to quantify directly the [PROTO]/[heme] ratio. This new approach to blood porphyrin assay should find extensive application in such public health problems as lead intoxication and iron deficiency.

Absorption and emission spectra and emission quantum yields are given for free-base (H/sub 2/), Zn, Cu, and Pd derivatives of tetrakis(perfluorophenyl)porphyrin (TFPP). The four-orbital model is used to rationalize differences in the optical properties among the derivatives of TFPP and the same derivatives of porphine (P), octaethylporphyrin (OEP), and tetraphenylporphyrin (TPP). It is concluded from absorption data that the energy difference between the two excited singlets, i.e., /sup 1/E(a/sub 2u/,e/sug g/) - /sup 1/E(a/sub 1u/,e/sub g/), decreases along the series Pd > Cu > Zn > H/sub 2/ and also along the series OEP > P > TFPP > TPP. The theory and date are reviewed, and it is concluded that the energy difference between the two excited triplets, i.e., /sup 3/E(a/sub 2u/,e/sub g/) - /sup 3/E(a/sub 1u/,e/sub g/), also decreases along these series. However the condition of degeneracy, e.g., /sup 1/E(a/sub 2u/,e/sub g/) - /sup 1/E(a/sub 1u/,e/sub g/) = 0, occurs for different molecules in the singlet and triplet cases. Theory also suggests that if /sup 3/E(a/sub 2u/,e/sub g/) > /sup 3/E(a/sub 1u/,e/sub g), the molecule should form a /sup 2/A/sub 1u/ cation radical and if /sup 3/E(a/sub 2u/,e/sub g/) < /sup 3/E(a/sub 1u/,e/sub g/) the molecule should formmore » a /sup 2/A/sub 2u/ radical. 4 figures, 2 tables.« less

The absorption spectrum of single and oriented crystals of iodine has been investigated in the wavelength region 7000–3000 A. Four strongly polarized bands and one weakly polarized absorption band have been observed, all of which are polarized in the ac plane of the crystal. All of the absorption bands are approximately 1000 cm−1 wide. The crystal‐band theory for iodine given by Rosenberg has been extended, and the effects of exchange and of spin—orbit coupling have been qualitatively considered. Three models are discussed with varying relative importance of spin—orbit and crystal energies. These models are correlated, and the strong crystal force model is used to interpret the experimental observations.