The effect of experimentally induced anxiety on pain perception was examined using a signal detection discrimination experiment. The experimental condition consisted in unsignalled application of very painful stimuli which substantially raised state anxiety. The discrimination task included the total range of painful stimuli. The results indicated a range-specific effect of anxiety on pain, particularly on increased sensitivity in the upper range of intensities. The importance of testing the effect of anxiety over the whole range of intensities is stressed. That prior work considered only one intensity level may be the main reason why previous signal detection studies about pain and anxiety showed contradictory results.

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We have studied the binding of the CAP protein to an 18 base pair lac promoter sequence comprising the core of the CAP recognition sequence. Specific binding of this sequence was established by competition binding assays and comparison of the relative affinities of a number of lac promoter, lac operator, and unspecific sequences of different lengths. The effect of the binding of CAP to the 18 base pair promoter sequence and, for comparison, to an 18 base pair symmetric operator and an oligonucleotide of unrelated sequence have been studied by 1H NMR. Binding of CAP does not bring about any changes in the chemical shift values of the imino proton resonances of the DNA, but causes the selective line broadening of two of the resonances. The comparison of these data with results of gel retardation assays published previously (1) allows the identification and localization of a kink induced in the DNA by the CAP binding to its specific site on the lac promoter.

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