Dissociative Experiences Scale

Dissociation is the core feature of the dissociative disorders it is defined by the DSM-IV as a disruption in the usually integrated functions of consciousness, memory, identity, or perception of the environment (American Psychiatric Association, 1994, p. 477). Dissociation is usually assessed as a continuum, most often using the Dissociative Experiences Scale (DES Bemstein-Carlson Putnam, 1986), a 28-item self-report measure. The DES items are rated on a scale reflecting the frequency of dissociative experiences (O-to-100% in 10% intervals). Factor analyses of DES items have led to the development of three subscales (Carlson et al., 1993 Frischholz, Braun, Sachs, Schwartz, 1991 Ross, Joshi, Currie, 1991). They are (a) Absorption, which reflects dissociation from surroundings (e.g., daydreaming) (b) Amnesia, which reflects dissociation from past experiences and (c) Depersonalization-Derealization, which reflects dissociation from the body or senses. 

Carlson, E. B., Putnam, F. W., Ross, C. A., Torem, M., Coons, P., Dill, D., et al. (1993). Validity of the Dissociative Experiences Scale in screening for multiple personality disorder A multi-center study. American journal of Psychiatry, 150, 1030-1036. 

Frischholz, E. J., Braun, B. G., Sachs, R. G., Schwartz, D. R. (1991). Construct validity of the Dissociative Experiences Scale (DES) I. The relationship between the DES and other self-report measures of DES. Dissociation Progress in the Dissociative Disorders, 4, 185-188. 

Leavitt, F. (1999). Dissociative experiences scale taxon and measurement of dissociative pathology Does the taxon add to an understanding of dissociation and its associated pathologies Journal of Clinical Psychology in Medical Settings, 6, 427-440. 

Fig. 4. Transient and equilibrium binding of ligand to cell surface receptors for the case of ligand concentration L approximately constant and equal to L . The fraction of total surface receptors bound, u, is shown, (a) The equilibrium value, eq, is plotted as a function of the logarithm of the ratio L0/KD. (b), (c) u is plotted as function of scaled time r for several values of the ratio Ln/Ku. The initial value and time course of u in (b) correspond to an association experiment. The initial value and time course of u in (c) correspond to a dissociation experiment.

Armentrout PB, Rodgers MT. Ab absolute sodium cation affinity scale threshold collision-induced dissociation experiments and ab initio theory. J Phys Chem A. 2000 104 2238-47. Amicangelo JC, Armentrout PB. Absolute binding energies of alkali-metal cation complexes with benzene determined by threshold collision-induced dissociation experiments and ab initio theory. J Phys Chem A. 2000 104 11420-32. 

Binding assays for the saxitoxins were conducted with homogenized rabbit brain and saxitoxin exchange-labelled with tritium at C-11 (92, 93). If the various saxitoxins were available with suitably intense radiolabels, then the equilibrium dissociation constant, K, could be measured directly for each. Since only saxitoxin is currently available with the necessary label, the binding experiments instead measure the ability of a compound to compete with radiolabelled saxitoxin for the binding site. The value obtained, Kj, corresponds to the uilibrium dissociation constant, K, that would be observed for the compound if it were measured directly. Affinity is defined for this assay as the reciprocal of Kj. The affinities of several of the saxitoxins (94) are summarized in Figure 11, expressed relative to saxitoxin and plotted on a logarithmic scale. 

In 1909, Sorenson described the development of the pH scale based on the work of Arrhenius and the characteristics of water. Experiments and the resulting calculations show that water dissociates into hydrogen ions (H+) and hydroxide ions (HO-) and that the product of their concentrations equals close to 10"14 ions in aqueous solution. From this, a pH scale from 0 to 14 was developed and the scale describing this relationship using the abbreviation pH was developed (in the older literature [13], one may encounter both the p and the h capitalized, i.e., as PH). Today, it is universally designated as pH [13,22]. 

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