The inhibitory effects of anti-tumor, bacterial filament forming platinum compounds, C14 ( B ) , and Pt (11) ( NH,) , (CH,) , CI, ( C ) on DNA, RNA and protein syntheses was measured by the incorporation of 3Hthymidine, 3H-uridine, and 3H-L-leucine, respectively, into an acid-insoluble polymer in human amnion A V 3 cells. Compound A , the most effective tumor-inhibiting platinum compound, was shown to selectively inhibit D N A synthesis below 5pM and to inhibit 3H-thymidine incorporation more rapidly than 3H-uridine or 3H-leucine incorporation at 2SpM. Like A, compounds B and C were also shown to inhibit all three processes after a 24-hour period of treatment at 2SpM. A correlation was established between the relative anti-tumor effectiveness of compounds A , B, and C and the extent of theirinhibitory effects. On the other hand,

Experimental data on semiconducting organic substances are usually processed by use of the two-constant equation, σ(T) = σ0exp(−E / 2kT). Evidence from a number of cases now indicates that σ0 is dependent on E, when the equation is applied to certain single substances where E varies with preparation. A three-constant equation of the following form applies: σ(T) = σ0′ exp(E / 2kT0) exp(−E / 2kT) where T0 is a new constant, the “characteristic temperature” of the substance. A method of evaluating σ0′ and T0 is to vary the activation energy for semiconduction by any of at least three processes: (1) hydration of the crystals; (2) formation of weak donor–acceptor complexes; (3) using different cis–trans isomers of the substance when possible. One method of evaluating the constants is to plot logσ0vs E. The slope of this line yields (2kT0)−1, and the intercept yields σ0′. Other methods are possible and yield consistent results. These methods are demonstrated for the substances oxidized cholesterol, retinal, and nucleic acids. The implication of these results is that the Meyer–Neldel rule for compound inorganic semiconductors is valid for organic semiconductors as well. No reasonable theoretical explanation has yet been proposed to account for this rule.

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