Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DISSOCIATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources
PubMed2002

Malingering dissociative identity disorder: objective and projective assessment.

Verification of dissociative identity disorder presents challenges given the complex nature of the illness. This study addressed the concern that this disorder can be successfully malingered on objective and projective psychological tests. 50 undergraduate women were assigned to a Malingering or a Control condition, then completed the Rorschach Inkblot Test and the Dissociative Experiences Scale II. The Malingering group were asked to simulate dissociative identity disorder; controls received instructions to answer all materials honestly. Analysis indicated that malingerers were significantly more likely to endorse dissociative experiences on the Dissociative Experiences Scale II in the range common to patients with diagnosed dissociative identity disorder. However, on the Rorschach there were no significant differences between the two groups. Results suggest that the assessment of dissociative identity disorder requires a multifaceted approach with both objective and projective assessment tools. Research is needed to assess these issues in clinical populations.

Adolescent↗
PubMed2005

Discriminating among diagnostic categories using the Dissociative Disorders Interview Schedule.

The Dissociative Disorders Interview Schedule was administered to 1,308 subjects in eight diagnostic categories, including 296 with dissociative identity disorder. The study tested three hypotheses: (1) the Mahalanobis distance between dissociative identity disorder and each of seven other diagnostic categories would be large, (2) the closest diagnostic category to dissociative identity disorder would be dissociative disorder not otherwise specified, and (3) nondissociative diagnostic categories would be closer to each other than any one to dissociative identity disorder. All three hypotheses were confirmed by these data. The findings support the conclusion that dissociative identity disorder is a discrete category or taxon.

Adolescent↗
PubMedDate not supplied

The concept of an organic dissociative syndrome: what is the evidence?

The question of whether organic conditions, such as complex partial seizures, can cause dissociative symptoms is controversial. Although a diagnostic category for organic dissociation is included in the tenth edition of International Classification of Disease, it has never been identified in the Diagnostic and Statistical Manual. Its inclusion in the upcoming DSM-IV is currently under debate. This article surveys representative literature regarding the role of organic factors in the causation of dissociative symptoms and considers the differential diagnosis of organic dissociation from current and historic perspectives. Dissociative symptoms and disorders (including amnesia, fugue, depersonalization, multiple personality, automatisms, and certain furors) can be induced by a variety of medications, drugs of abuse, and medical illnesses or conditions affecting cerebral function. Organic dissociation can be distinguished from intoxication, amnestic disorder, and delirium. Psychiatric nosology and our conceptualization of altered mental states and functions would benefit from use of the concept of an organic dissociative syndrome, which has clinical, neurophysiologic, and medicolegal significance. Such a category should be included in DSM-IV.

Diagnosis, Differential↗
PubMed1999

Naltrexone in the treatment of dissociative symptoms in patients with borderline personality disorder: an open-label trial.

BACKGROUND: Dissociative phenomena, including flashbacks, are common in patients with borderline personality disorder and posttraumatic stress disorder (PTSD). Although dissociative symptoms can be severe and may interfere with psychotherapy, there is no established pharmacotherapy for these symptoms. Evidence suggests that alterations of the endogenous opiate system contribute to dissociative symptoms in patients with borderline personality disorder and PTSD. METHOD: We treated 2 groups of female borderline personality disorder patients (N = 13, with an overlap of 5 patients between the 2 groups; all met the diagnostic criteria of DSM-IV and the revised Diagnostic Interview for Borderline Patients) who experienced prominent dissociative phenomena including flashbacks with the nonselective opiate receptor antagonist naltrexone, 25 to 100 mg q.i.d., for at least 2 weeks. A self-rated questionnaire measuring dissociation, analgesia, tonic immobility, and tension (DAISS) was applied to 9 patients, who completed it for 7 consecutive days before and during treatment with naltrexone. In addition, 9 patients (with an overlap of 5 patients from the other group) completed a flashback protocol. RESULTS: DAISS scores reflected a highly significant reduction of the duration and the intensity of dissociative phenomena and tonic immobility as well as a marked reduction in analgesia during treatment with naltrexone. Six of 9 patients reported a decrease in the mean number of flashbacks per day. CONCLUSION: These observations support the hypothesis that an increased activity of the opioid system contributes to dissociative symptoms, including flashbacks, in borderline personality disorder and suggest that these symptoms may respond to treatment with opiate antagonists. In view of these results, a placebo-controlled, double-blind study to assess the potential benefit of naltrexone in a more rigorous way appears justified.

Adolescent↗
PubMedDate not supplied

[Based on one case of dissociative disorder: a conceptual review].

Based on the description of a clinical case treated by the authors, and diagnosed of dissociative disorder, a review of the diagnosis of dissociative disorder and its polemics is carried out. The authors discuss concepts such as dissociation and hysteria, their historic evolution and their relationships. Some modern cognitive theories on dissociative disorders and their relationship or opposition to psychodynamic theories are presented. The differences between dissociation and repression with these two different approaches are also mentioned. The authors conclude that at the present time important questions must be solved in the area of dissociative disorders in order to progress in the psychiatric knowledge of dissociative processes.

Adult↗
PubMed2004

Dissociative disorder in children. A case study.

Dissociative disorder is well-known in adulthood but in many cases it begins in childhood where it is usually not taken into consideration, rarely diagnosed, and often mistaken with borderline disorders. In childhood dissociation is well-defined: in a dimensional way by the presence of the dissociation symptoms over 2 SD and in a categorial view by the presence of primary symptoms. We made a psychiatric assessment on a child aged 11 years and 7 months, who said he heard "voices in his head". The assessment included: Children Dissociative Checklist (CDC), Adolescent Dissociative Experience Scale (A-DES), Children Depression Inventory (CDI), Wechsler Intelligence Scales for Children-Revised (WISC-R), Strength and Difficulties Questionnaire (SDQ), Children Behaviour Check-list (CBCL), (Scale Disturbi Attenzione Genitori, parent attention deficit scale, SDAG), Parent Conners Questionnaire, free conversation, a drawing, a neurological examination, an EEG-Holter and a semistructured psychiatric interview: K-SADS PL 1.0. SDQ, CDI and CBCL showed pathological scores in every area. K-SADS PL 1.0 excluded schizophrenia and showed: attention deficit, disthymic disorder, generalized anxiety disorder, oppositive-defiant disorder and conduct disorder with rage episodes, like borderline disorder. I.Q. was 76, SDAG (total 46) and Conners (mean points 1.81) showed a high score, simulating Attention Deficit with Hyperactivity disorder (ADHD). The presence of primary symptoms, like dissociative amnesia and very high scores in CDC (23, mean score for MPD) and in A-DES (85, mean 4.2) are useful for diagnoses. Dissociative disorder also exists in childhood, but it should be differentiated from ADHD and borderline disorder.

Child↗
PubMed1989

Substance-induced dissociative disorders and psychiatric nosology.

Transient amnesias, fugues, twilight states, automatisms, depersonalization, and furors or explosive disorders can occur in association with, or be caused by, various medications or substance-induced organic brain states. Agents capable of precipitating dissociative-like states include alcohol, barbiturates and similarly acting hypnotics, benzodiazepines, scopolamine, clioquinol, beta-adrenergic blockers, marijuana and certain psychedelic drugs, general anesthetics, and others. The presentations of substance-induced dissociative states may resemble those of functional dissociative disorders, or organic and psychogenic dissociative factors may coexist and be intertwined or indistinguishable. Organic dissociative states are distinct from intoxication, amnestic disorder, frank delirium, or other organic mental disorders as specified in DSM-III and DSM-III-R, yet these diagnostic manuals have no inclusive category or coherent nosological approach to dissociative states not strictly psychogenic in etiology. Substance-induced and other organic dissociative disorders can have clinical, medicolegal, and neuropsychological significance. They provide a unique opportunity for the study of mind-brain relationships and should be included in psychiatric nosology.

Dissociative Disorders↗
PubMed2005

Dissociation of alkaliated alanine in the gas phase: the role of the metal cation.

The dissociation of prototypical metal-cationized amino acid complexes, namely, alkaliated alanine ([Ala+M]+, M+ = Li+, Na+, K+), was studied by energy-resolved tandem mass spectrometry with an ion-trap mass analyzer and by density functional theory. Dissociation leads to formation of fragment ions arising from the loss of small neutrals, such as H2O, CO, NH3, (CO+NH3), and the formation of Na+/K+. The order of appearance threshold voltages for different dissociation pathways determined experimentally is consistent with the order of critical energies (energy barriers) obtained theoretically, and this provides the necessary confidence in both experimental and theoretical results. Although not explicitly involved in the reaction, the alkali metal cation plays novel and important roles in the dissociation of alkaliated alanine. The metal cation not only catalyzes the dissociation (via the formation of loosely bound ion-molecule complexes and by stabilizing the more polar intermediates and transition structures), but also affects the dissociation mechanisms, as the cation can alter the shape of the potential energy surfaces. This compression/expansion of the potential energy surface as a function of the alkali metal cation is discussed in detail, and how this affects the competitive loss of H2O versus CO/(CO+NH3) from [Ala+M]+ is illustrated. The present study provides new insights into the origin of the competition between various dissociation channels of alkaliated amino acid complexes.

Alanine↗
PubMed2002

Cluster ions derived from sodium and potassium tetrafluoroborate and their collision induced dissociation in an ion trap mass spectrometer.

Electrospray ionization was used to produce distributions of gas-phase cluster ions from solutions of sodium and potassium tetrafluoroborate. The majority of the cluster species followed the trend (MBF(4))(n)M(+), where M=Na and K. The values of n, for both salts, ranged from 1-15. Collision induced dissociation (MS/MS and MS(n)) in an ion trap mass spectrometer was used to determine the dissociation pathways for the cluster ions. The (NaBF(4))(n)Na(+) cluster ions fragmented via two pathways: (a) the loss of one or multiple neutral BF(3) molecules and (b) the loss of one or more NaBF(4) units. Of the two, the product ions corresponding to the loss of BF(3) units were more prominent. Unlike the Na salt, the (KBF(4))(n)K(+) cluster ions decomposed primarily by the loss of one or multiple KBF(4) units. Similar differences in dissociation behavior were observed when the heated transfer capillary, normally used to desolvate ions, was used to investigate cluster ion stability to thermal degradation and dissociation. The dissociation profiles (decrease in ion abundance with increasing activation amplitude) for several (NaF)(n)Na(+) and (KF)(n)K(+) cluster ions were measured and compared to probe the influence of the relative stability of the alkali fluorides (NaF and KF) on the dissociation behavior exhibited by the tetrafluoroborate cluster distributions. We found that the (NaF)(n)Na(+) cluster ions required higher activation amplitudes to induce fragmentation than the corresponding (KF)(n)K(+) species, indicative of stronger ionic bonding and higher gas-phase stability for the former. This in turn indicates that the reaction pathway involving only the loss of one or multiple units of BF(3), favored for the (NaBF(4))(n)Na(+) cluster series, but not for the analogous (KBF(4))(n)K(+) series, may be due to the high gas-phase stability of NaF, and relatively lower stability of KF, towards dissociation.

Journal Article↗
PubMed1997

Dissociation between categorical and coordinate spatial computations: modulation by cerebral hemispheres, task properties, mode of response, and age.

Kosslyn suggested a dissociation of two kinds of spatial representations: categorical and coordinate, the former computed by the left hemisphere and the latter by the right hemisphere. In addition, with practice, a "categorization" of the coordinate computation would appear. These suggestions resulted largely from an experiment, replicated by others, in which the subjects had to estimate the relative position of a dot and a line by giving an oral response, and feedback was provided. The present series of five experiments was an attempt to test whether this finding could be generalized, under several methodological manipulations, some of which have already been used by researchers in separate studies. In the five experiments, accuracy was a more contributive dependent variable than correct latencies, and practice effects on the task X field interaction were not verified. Experiments 1-3 concerned the kind of response. When a manual instead of an oral response was required (Experiment 1; n = 32 Ss), the expected dissociation was observed (as well as when the latency of responses made by the right hand were studied). When the number of oral responses was increased from two (a binary choice) to eight, the dissociation was still observed for accuracy but disappeared when a more liberal criterion of accuracy was used to reduce the considerable task effect (Experiment 2; n = 32 Ss), or when response requirements were equated for both tasks (Experiment 3; n = 32 Ss). In Experiment 4 (n = 32 Ss), a manual response was called but the feedback was removed and the task dissociation disappeared. Finally, the task dissociation observed in Experiment 1 was not verified when a sample of elderly subjects was enrolled (Experiment 5; n = 32 Ss). However, age per se was the source of an interesting additional dissociation since only the coordinate computation was age sensitive. Our results suggest that the dissociation proposed by Kosslyn between the computation of categorical vs coordinate spatial relationships is highly unstable and sensitive to subtle methodological factors (vocal vs manual response, presence vs absence of feedback, binary vs "continuous" response, age) which could preclude its general application.

Adolescent↗
PubMed2001

Linkage of EcoRI dissociation from its specific DNA recognition site to water activity, salt concentration, and pH: separating their roles in specific and non-specific binding.

We have measured the dependencies of both the dissociation rate of specifically bound EcoRI endonuclease and the ratio of non-specific and specific association constants on water activity, salt concentration, and pH in order to distinguish the contributions of these solution components to specific and non-specific binding. For proteins such as EcoRI that locate their specific recognition site efficiently by diffusing along non-specific DNA, the specific site dissociation rate can be separated into two steps: an equilibrium between non-specific and specific binding of the enzyme to DNA, and the dissociation of non-specifically bound protein. We demonstrated previously that the osmotic dependence of the dissociation rate is dominated by the equilibrium between specific and non-specific binding that is independent of the osmolyte nature. The remaining osmotic sensitivity linked to the dissociation of non-specifically bound protein depends significantly on the particular osmolyte used, indicating a change in solute-accessible surface area. In contrast, the dissociation of non-specifically bound enzyme accounts for almost all the pH and salt-dependencies. We observed virtually no pH-dependence of the equilibrium between specific and non-specific binding measured by the competition assay. The observed weak salt-sensitivity of the ratio of specific and non-specific association constants is consistent with an osmotic, rather than electrostatic, action. The seeming lack of a dependence on viscosity suggests the rate-limiting step in dissociation of non-specifically bound protein is a discrete conformational change rather than a general diffusion of the protein away from the DNA.

Binding Sites↗
PubMed1996

Energetics of cyclodextrin-induced dissociation of insulin.

The energetics of dissociation of bovine insulin in aqueous solution have been investigated by sensitive dilution microcalorimetry. Cyclodextrins increase dissociation of insulin oligomers in a manner consistent with their interaction with protein side chains. For example, assuming monomer-dimer equilibrium, in the absence of cyclodextrins the calorimetric dilution data (25 degrees C, pH 2.5) indicate a dimer dissociation constant (K(diss)) of about 12 microM and an endothermic dissociation enthalpy (delta H(diss) of +41 kJ mol-1. Addition of methyl-beta-cyclodextrin (up to 200 mM) makes dissociation significantly more endothermic (delta H(diss) = 79 kJ mol-1) and reduces the apparent dimer dissociation constant by more than two orders of magnitude (K(diss) approximately 1.7 mM). Qualitatively similar results are observed with alpha-cyclodextrin and other beta-cyclodextrin derivatives. Cyclodextrin-induced insulin dissociation is also observed at pH 7.4.

Animals↗
PubMed1984

Dissociation and oxygen equilibrium properties of the extracellular hemoglobin of Eisenia foetida.

The dissociation and oxygen equilibrium properties of whole blood and the purified hemoglobin from Eisenia foetida were compared. Oxygen affinities agreed approximately with each other in the range of pH 6.0 to 9.5. The values of n1/2 were higher in whole blood than in the purified hemoglobin between pH 7.0 and 9.5. The maximum values, obtained near pH 8, were about 6 in whole blood and 3.5 in the purified hemoglobin. In the purified hemoglobin, alkaline dissociation started at pH 7.8, and the approximately 60 S whole molecule dissociated completely into approximately 10 S and 5-6 S components at pH 9.1. In whole blood, however, the dissociation started at pH 8.2 and the complete disappearance of the approximately 60 S molecule occurred at pH 9.6. The values of n1/2 for the dissociation products were lower than those of the purified hemoglobin between pH 7.0 and 9.0. The value of n1/2 decreased with increasing dissociation of the approximately 60 S whole molecule with a pH rise in both whole blood and the purified hemoglobin. Addition of CaCl2 or MgCl2 up to 10 mM to the purified hemoglobin at pH 8.0-8.1 induced increases in oxygen affinity and cooperativity and in the stability of the approximately 60 S whole molecule. The effect on the oxygenation properties was greater with CaCl2 than MgCl2 at the same molar concentration. The stabilizing effect on the approximately 60 S molecule was almost the same with both CaCl2 and MgCl2. These results suggest that the dissociation of property of the hemoglobin in whole blood is controlled by both Ca2+ and Mg2+, and that its oxygenation property is controlled by Ca2+.

Animals↗
PubMed1982

Dissociation of the glycoprotein IIb-IIIa complex in isolated human platelet membranes. Dependence of pH divalent cations.

The platelet membrane glycoproteins IIb and IIIa normally exist as a complex which forms a predominant immunoprecipitate after crossed immunoelectrophoresis of Triton-X-100-solubilized platelets. Dissociation of the complex occurs by solubilization in the presence of EDTA or EGTA at pH 8.7 and is readily verified by crossed immunoelectrophoresis. Incubations of isolated membranes with EDTA or EGTA at various pH levels were performed. Removal of the chelators and solubilization showed no dissociation of the glycoprotein IIb-IIIa complex in membranes incubated at pH below 8.0. At pH above 8.0 a dissociation which increased with increasing pH was seen. Under these conditions, dissociation appears to take place already in the intact membranes. The tendency of the glycoprotein IIb-IIIa complex to become dissociated with EDTA or EGTA at increasing pH seems to be due to increased chelating capacity of the chelators concomitant with a decreased chelating capacity of glycoprotein IIb and IIIa. The divalent cations Ca2+ and Mg2+, but not Cu2+, Zn2+, Mn2+ or Sr2+, in molar concentrations below that of EGTA were able to prevent the dissociation of the glycoprotein IIb-IIIa complex by the chelator at pH 9.0, indicating that Ca2+ as well as Mg2+ can be used to keep the complex together. In some experiments it was possible to reverse the dissociation in the membranes after removal of EDTA. At pH 7.5 reassociation occurred within 15 min whether divalent cations were added or not. At pH 9.0. reassociation occurred within 2 h provided Ca2+ was present. The tendency of glycoprotein IIb and IIIa to form a complex thus appeared to be most pronounced over the physiological pH range and to be a rapid process in platelet membranes under such conditions.

Blood Platelets↗
PubMed1981

Factor-dependent dissociation of wheat germ ribosomes.

Ribosome dissociation factor has been found in wheat germ acetone powder extracts. Further purification of the crude extract by pH an ammonium sulfate fractionations, DEAE-cellulose and CM-Sephadex column chromatography has resulted in the separation of two active fractions. The possibility that ribosome dissociation activity exhibited by either fraction is due to protease or nuclease is considered unlikely, based on results of experiments involving ribosome dissociation kinetics, subunit structural integrity, and treatment with a serine protease inhibitor. Wheat germ ribosome dissociation factor is not species-specific. Dissociation factor from both fractions will promote the dissociation of Escherichia coli 70-S as well as Artemia salina 80-S ribosomes. Although both dissociation factor activities show the same dependence on K+ and Mg2+ for optimal activity, the two activities exhibit significant differences in their sensitivity to sulfhydryl reagents and heat, and in their dependence on incubation temperature for activity. Certain properties of both factors suggest that neither factor is initiation factor eIF-3; however, the possibility that one or both factors are subunits of initiation factor eIF-3 remains to be determined.

Animals↗
PubMed1981

Kinetics of dissociation of quinoxaline antibiotics from DNA.

The kinetics of detergent-induced dissociation of triostins A and C and quinomycin C from DNA have been investigated. All three antibiotics dissociate from poly(dA-dT) and poly(dG-dC) in a simple first-order fashion whereas their dissociation from a natural DNA (calf thymus) is complex, requiring three exponential terms for its complete description. This behaviour is attributed to sequence-selectivity on the part of the drugs and seems to represent dissociation from different classes of intercalative binding site. The time constants of dissociation are better resolved for quinomycins than for triostins, consistent with the view that quinomycins are more sequence-specific in their interaction with DNA, but it is not possible to identify any class of binding site with the alternating purine-pyrimidine sequences of the synthetic polydeoxynucleotides. In general, the triostins dissociate an order of magnitude faster than the corresponding quinomycins. This is attributable to a larger entropy of activation, presumably reflecting greater flexibility of the octapeptide ring when the cross-bridge is a disulphide as opposed to the slightly shorter thioacetal found in quinomycins. The longest time constant in the dissociation of each of the four quinoxaline antibiotics from calf thymus DNA correlates well with its antibacterial potency, in agreement with the conclusion that the biological effects result from impairment of the role of DNA as a template for polymerase activity.

Animals↗
PubMed1986

The hepatic galactosyl receptor system: two different ligand dissociation pathways are mediated by distinct receptor populations.

After internalization of 125I-asialo-orosomucoid (ASOR) by isolated rat hepatocytes, ligand dissociates by two kinetically distinct pathways (Oka and Weigel, J. Biol. Chem. 257, 10,253, 1983). These slow and fast dissociation pathways correspond to two functionally different subpopulations of cell surface galactosyl receptors designated, respectively, State 1 and State 2 receptors. Freshly isolated cells or cells equilibrated below 24 degrees C express only State 1 receptors. Cells equilibrated at 37 degrees C express both State 1 and State 2 receptors. Ligand dissociation after internalization of surface-bound 125I-ASOR was measured using the permeabilizing detergent, digitonin. The slow dissociation pathway was mediated by State 1 receptors and was the only pathway expressed by cells which were freshly isolated or had been equilibrated at 24 degrees C. State 2 receptors are expressed at temperatures above about 20 degrees C, and both the fast and slow dissociation pathways occurred in cells equilibrated at 37 degrees C. State 2 receptors therefore mediate the rapid dissociation pathway. Dissociation and subsequent degradation of specifically bound ligand routed in either pathway were complete, respectively, within 3 and 6 hrs.

Animals↗
PubMed1982

Serotonin modulates the dissociation of [3H]imipramine from human platelet recognition sites.

The dissociation of [3H]imipramine from human platelet membrane recognition sites was studied. Simple exponential dissociation kinetics were observed indicating an apparent homogeneous class of sites which dissociate by a first order rate process. Inclusion of serotonin in the medium dramatically decreased the dissociation rate. At 0 degree C half-times of dissociation were 61.7 and 170 min in the absence and presence of serotonin, respectively. Other biogenic amines were ineffective in altering the dissociation kinetics. It is suggested that serotonin controls [3H]imipramine dissociation from an allosterically coupled site residing on a larger macromolecular complex.

Binding Sites↗