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At least 19 recordsLinked to original sources

PubMed2005

Effective novel dissociation methods for intact protein: heat-assisted nozzle-skimmer collisionally induced dissociation and infrared multiphoton dissociation using a Fourier transform ion cyclotron resonance mass spectrometer equipped with a micrometal electrospray ionization emitter.

Heating of a nano-electrospray ionization (nanoESI) source can improve the dissociation efficiency of collisionally induced dissociation (CID) methods, such as nozzle-skimmer CID (NS-CID) and infrared multiphoton dissociation (IRMPD), for large biomolecule fragmentation. A metal nanoESI emitter was used due to its resistance to heating above 250 degrees C. This novel method for the dissociation of large biomolecular ions is termed "heat-assisted NS-CID" (HANS-CID) or "heat-assisted IRMPD" (HA-IRMPD). Multiple charged nonreduced protein ions (8.6 Da ubiquitin, 14 kDa lysozyme, and 67 kDa bovine serum albumin) were directly dissociated by HANS-CID and HA-IRMPD to effectively yield fragment ions that could be assigned. The fragment ions of ubiquitin by HANS-CID can be analyzed by tandem mass spectrometry (MS/MS) using sustained off-resonance irradiation CID (SORI-CID) and IRMPD. In addition, a native large protein, immunoglobulin G (IgG, 150 kDa), was efficiently dissociated by HA-IRMPD. The product ions that were obtained reflected the domain structure of IgG. However, these product ions of IgG and lysozyme were not dissociated by MS/MS using the same heating energetic methods such as IRMPD and SORI-CID.

Animals↗

PubMed2005

Structural characterization of the GM1 ganglioside by infrared multiphoton dissociation, electron capture dissociation, and electron detachment dissociation electrospray ionization FT-ICR MS/MS.

Gangliosides play important biological roles and structural characterization of both the carbohydrate and the lipid moieties is important. The FT-ICR MS/MS techniques of electron capture dissociation (ECD), electron detachment dissociation (EDD), and infrared multiphoton dissociation (IRMPD) provide extensive fragmentation of the protonated and deprotonated GM1 ganglioside. ECD provides extensive structural information, including identification of both halves of the ceramide and cleavage of the acetyl moiety of the N-acetylated sugars. IRMPD provides similar glycan fragmentation but no cleavage of the acetyl moiety. Cleavage between the fatty acid and the long-chain base of the ceramide moiety is seen in negative-ion IRMPD but not in positive-ion IRMPD of GM1. Furthermore, this extent of fragmentation requires a range of laser powers, whereas all information is available from a single ECD experiment. However, stepwise fragmentation by IRMPD may be used to map the relative labilities for a series of cleavages. EDD provides the alternative of electron-induced fragmentation for negative ions with extensive fragmentation, but suffers from low efficiency as well as complication of data analysis by frequent loss of hydrogen atoms. We also show that analysis of MS/MS data for glycolipids is greatly simplified by classification of product ion masses to specific regions of the ganglioside based solely on mass defect graphical analysis.

Animals↗

PubMed2006

[Screening for major dissociative disorders with the FDS, the German version of the Dissociative Experience Scale].

UNLABELLED: The prevalence of major dissociative disorders (dissociative identity disorder, DID and similar forms of dissociative disorder not otherwise specified, DDNOS) in clinical samples is about 5 %. Despite their frequency, major dissociative disorders are often overseen for a long time. Screening-scales have proved to be effective to support clinical diagnosis. The aim of this study was to test, whether the Fragebogen für dissoziative Symptome (FDS), the German version of the Dissociative Experiences Scale (DES), differentiates between patients with dissociative disorders, non-dissociative disorders and non-clinical controls. Additionally, an optimal FDS-cutoff for a more detailed differential-diagnostic evaluation of the dissociative symptomatology should be identified. 150 participants with DID (group DID: n = 44), DDNOS (DDNOS: n = 22), posttraumatic disorders (TRAUMA: n = 20), other non-dissociative disorders (non-TRAUMA: n = 34) and non-clinical controls (KG: n = 30) completed the FDS. In the five diagnostic groups, mean values were calculated and compared for the FDS, DES and FDS-20. Via receiver-operating-curves the cutoff-scores, which differentiated best between participants with and without major dissociative disorders, were identified. FDS, DES and FDS-20 differentiate significantly between patients with and without major dissociative disorders. For all scales, there were significant differences between the diagnostic groups, with mean-scores decreasing continuously from the groups DID to DDNOS and TRAUMA. Between the groups non-TRAUMA and KG tendencies were found in the predicted direction. The optimal cutoff-scores to differentiate between participants with and without major dissociative disorders were 13 (FDS/FDS-20) and 15 (DES). Using these cutoff-scores, at least 90 % of the patients with major dissociative disorders could be identified correctly (sensitivity). The specifity of the scales was 0.89 to 0.90. CONCLUSION: Screening for major dissociative disorders with the FDS, DES and FDS-20 allows to identify patients with or without major dissociative disorders correctly in about 90 % of the cases. Therefore, the FDS should be used routinely in psychiatric and psychotherapeutic clinics and practices to identify high risk patients. Such a procedure would be an important step towards an improvement of the diagnostic and therapeutic care of patients with major dissociative disorders, which is still often unsatisfactory at present.

Adolescent↗

PubMed2006

The multidimensional inventory of dissociation (MID): A comprehensive measure of pathological dissociation.

This article describes the development and validation of the Multidimensional Inventory of Dissociation (MID). The MID is a 218-item, self-administered, multiscale instrument that comprehensively assesses the phenomenological domain of pathological dissociation and diagnoses the dissociative disorders. The MID measures 14 major facets of pathological dissociation; it has 23 dissociation diagnostic scales that simultaneously operationalize (1) the subjective/ phenomenological domain of pathological dissociation and (2) the hypothesized dissociative symptoms of dissociative identity disorder (Dell, 2001a). The MID was designed for clinical research and for diagnostic assessment of patients who present with a mixture of dissociative, posttraumatic, and borderline symptoms. The MID demonstrated internal reliability, temporal stability, convergent validity, discriminant validity, and construct validity. The MID also exhibited incremental validity over the Dissociative Experiences Scale (DES) by predicting an additional 18% of the variance in weighted abuse scores on the Traumatic Experiences Questionnaire (TEQ). Confirmatory factor analysis (CFA) did not support a one-factor model of the MID's clinical scales (i.e., the 14 facets and the 23 diagnostic symptoms). In contrast, however, CFA of the MID's factor scales (Dell & Lawson, 2005) has strongly supported a one-factor model. It was concluded that both the MID's 168 dissociation items and the construct of pathological dissociation have a second-order, unifactorial structure.

Adult↗

PubMed2003

Evidence for associations among somatoform dissociation, psychological dissociation and reported trauma in patients with chronic pelvic pain.

This study investigates somatoform as well as psychological dissociation, somatization and reported trauma among patients with chronic pelvic pain (CPP). Women with CPP (n = 52) who were newly referred to a gynecology department, or whose pain had resisted treatment, completed standardized self-report questionnaires and received a structured interview for DSM-IV dissociative disorders. The prevalence of dissociative disorders in the sample was very low. As hypothesized, self-reported somatoform dissociation was positively correlated with self-reported psychological dissociation and features of DSM-IV dissociative disorders; women who reported more serious psychic trauma, in particular sexual and physical abuse, experienced more somatoform and psychological dissociation than women reporting less trauma, or no trauma at all; and the association of somatoform dissociation and reported trauma was stronger than the association of psychological dissociation and trauma. Physical abuse/life threat posed by a person predicted somatoform dissociation best. The results are consistent with findings among psychiatric patients, and, therefore, strengthen the thesis that somatoform dissociation, (features of) dissociative disorder, and reported trauma are strongly intercorrelated phenomena.

Adult↗

PubMed2000

The differential diagnosis of epilepsy, pseudoseizures, dissociative identity disorder, and dissociative disorder not otherwise specified.

The authors review the co-occurrences of dissociative symptoms and disorders with epilepsy and pseudo-seizures and examine newer diagnostic instruments that assist in accurate diagnosis of persons with concomitant seizure behaviors and dissociative symptoms. They also review seizure behaviors and electroencephalographic findings in persons with dissociative identity disorder (DID) and dissociative disorder not otherwise specified (DDNOS) and dissociative symptoms in persons with epilepsy and with pseudoseizures. Dissociative symptoms in 15 patients with epilepsy and 15 with pseudo-seizures were examined using the Dissociative Experiences Scale (DES) and the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D). On the SCID-D, pseudo-seizure patients had significantly higher dissociative symptom scores than epileptic patients, but DES scores did not reliably distinguish epileptic and pseudo-seizure patients. Misdiagnosis of persons with seizures and dissociative symptoms can be avoided by careful adherence to DSM dissociative disorder criteria, the use of video-EEG monitoring, and systematic assessment of dissociative symptoms with the SCID-D.

Adult↗

PubMed2002

Dissociative phenomenology of dissociative identity disorder.

The goal of this study was to investigate the dissociative phenomenology of dissociative identity disorder (DID). The Multidimensional Inventory of Dissociation (MID) was administered to 34 patients with DID, 23 patients with dissociative disorder not otherwise specified (DDNOS), 52 patients with mixed psychiatric disorders, and 58 normal individuals. DID patients obtained significantly higher scores than the other three groups on 27 dissociation-related variables. DDNOS patients had significantly higher scores than normals and mixed psychiatric patients on 17 and 15 dissociation-related variables, respectively. The findings of the present study are virtually identical to a large body of replicated findings about the dissociative phenomenology of DID. This broad range of dissociation-related phenomena, which routinely occurs in individuals with DID, is largely absent from the DSM-IV-TR account of DID. Factor analysis of the 11 dimensions of dissociation that are measured by the MID extracted only one factor that accounted for 85% of the variance. It was concluded that dissociation is a unifactorial taxon or natural type that has different aspects or epiphenomena (i.e., amnesia, depersonalization, voices, trance, etc.).

Adult↗

PubMed2005

From dissociation to trauma? Individual differences in dissociation as predictor of 'trauma' perception.

In clinical literature, dissociative complaints are generally considered to be the result of traumatic experiences. However, it has been argued that dissociative complaints, in turn, may indulge over-reporting of traumatic experiences. Hence, correlations between dissociation and self-reported trauma may not only reflect the causal path from trauma to dissociation, but possibly also an increased trauma-item endorsement due to dissociation. To test the idea that dissociation fosters a positive response bias on trauma self-reports, participants completed a dissociation scale, and subsequently rated the perceived trauma of ambiguous stimuli. Results indicated that some dissociative complaints indeed predicted increased scores on the trauma ratings, while other manifestations of dissociation were negatively correlated with perceived trauma ratings. Hence, there is reason to argue that people differ in their readiness to perceive a situation as traumatic. However, the association between self-reported dissociation and the perception of 'trauma' is not quite clear-cut.

Adult↗

PubMed2004

The dissociation adiabaticity parameter and the strong field dissociation of HCl+.

In earlier work on H2+, we showed how a dissociation adiabaticity parameter, gammaDv identical with (Dv/2Upm)(1/2) (Dv is the dissociation energy from vibrational state v and U(pm) is the molecular ion system's ponderomotive energy), proposed by Walsh et al., can be modified and be a useful indicator of the strong field dissociation regime for a homonuclear diatomic. In the case of H2+, the new adiabaticity parameter, gamma(mol), indicates when a dissociation process can be most easily described as multiphoton above-threshold dissociation (gamma(mol)>1) and when it is better described using barrier-suppressed dissociation (gamma(mol)<1). In the case of a heteronuclear diatomic like HCl+, different electronic states can lead to different dissociation product channels to which are ascribed different gamma(mol) values. We show for a wide range of laser wavelengths and intensities that this adiabaticity parameter successfully predicts the type of dissociation dynamics (multiphoton above-threshold dissociation versus barrier-suppressed dissociation) on each electronic potential curve. We also discover that the dynamics in one electronic state can influence the dynamics in another at the same laser wavelengths and intensities, overriding the predictive capability of an adiabaticity parameter defined for a particular electronic state. Reasonable physical explanations are provided for these overriding cases.

Journal Article↗

PubMed2005

Development of the Hebrew-Multidimensional Inventory of Dissociation (H-MID): a valid and reliable measure of pathological dissociation.

The Multidimensional Inventory of Dissociation (MID; Dell, 2004b) has 168 dissociation items and 50 validity items. The MID assesses 14 major facets of dissociation, 23 symptoms of dissociation, and has 5 validity scales. The MID operationalizes (a) the subjective/ phenomenological domain of dissociation, and (b) 23 hypothesized symptoms of dissociative identity disorder (DID). This article describes the development of a Hebrew version of the MID (H-MID). In a sample of clinical and nonclinical research participants, the H-MID had strong internal consistency, temporal stability, and strong structural, convergent, discriminant, and construct validity. In addition, mean H-MID scores demonstrated incremental validity over the Hebrew Dissociative Experiences Scale (H-DES) by predicting an additional 17% of the variance in weighted trauma scores on the Traumatic Experiences Questionnaire (TEQ). Factor analysis of the H-MID extracted a single factor: dissociation. Both the MID and the subjective/phenomenological concept of pathological dissociation appear to have applicability not only in North America, but also in a heterogeneous Middle Eastern culture.

Adult↗

PubMed2001

A kinetic study of analyte-receptor binding and dissociation, and dissociation alone, for biosensor applications: a fractal analysis.

A fractal analysis is presented for (a) analyte-receptor binding and dissociation kinetics and (b) dissociation kinetics alone for biosensor applications. Emphasis is placed on dissociation kinetics. Data taken from the literature may be modeled, in the case of binding, using a single-fractal analysis or a dual-fractal analysis. The dual-fractal analysis represents a change in the binding mechanism as the reaction progresses on the surface. A single-fractal analysis is adequate to model the dissociation kinetics in the examples presented. Predictive relationships developed for the dissociation rate coefficient(s) as a function of the analyte concentration are of particular value since they provide a means by which the dissociation rate coefficients may be manipulated. Relationships are also presented for the binding and dissociation rate coefficients as a function of their corresponding fractal dimension, D(f), or the degree of heterogeneity that exists on the surface. When analyte-receptor binding or dissociation is involved, an increase in the heterogeneity on the surface (increase in D(f)) leads to an increase in the binding and in the dissociation rate coefficient.

Animals↗

PubMed1991

Diagnosing dissociative disorders in The Netherlands: a pilot study with the Structured Clinical Interview for DSM-III-R Dissociative Disorders.

OBJECTIVE: To improve the ability to diagnose dissociative disorders in The Netherlands, the authors conducted a study using a Dutch version of the Structured Clinical Interview for DSM-III-R Dissociative Disorders (SCID-D) with additional questions on childhood trauma and symptoms of borderline and histrionic personality disorders. METHOD: All interviews were audiotaped or videotaped and rated by two investigators separately. Forty-four patients (42 women and two men) participated in the study. Most of the patients had been referred for evaluation of dissociative symptoms; five had participated in a nationwide survey on incest. None of the patients had ever received a diagnosis of a dissociative disorder, and none had evidence of organic brain syndrome or mental retardation. All patients were in active treatment; 23 were being treated in an outpatient psychiatric service, 13 in an inpatient psychiatric service, and eight in private practice. Thirty-two patients had been psychiatric inpatients at least once. RESULTS: Four diagnostic groups of patients were identified: two with dissociative disorders (12 patients with multiple personality disorder and 11 with dissociative disorder not otherwise specified), one with DSM-III-R personality disorders (11 patients), and one without dissociative or personality disorders (10 patients). CONCLUSIONS: Dissociative disorders are clearly not only an American phenomenon. The diagnosis can be made outside of the United States if the symptoms are sought. The SCID-D proved to be a promising instrument.

Adolescent↗

PubMed1998

Degree of somatoform and psychological dissociation in dissociative disorder is correlated with reported trauma.

In this study, the prevalence and severity of traumatic experiences as reported by patients with dissociative disorders and with other DSM-IV psychiatric diagnoses were compared. Furthermore, the predictive value of emotional, physical, and sexual trauma with respect to somatoform and psychological dissociation was analyzed. In contrast with comparison patients, dissociative disorder patients reported severe and multifaceted traumatization. Physical and sexual trauma predicted somatoform dissociation, sexual trauma predicted psychological dissociation as well. According to the memories of the dissociative disorder patients, this abuse occurred in an emotionally neglectful and abusive social context. Pathological dissociation was best predicted by early onset of reported intense, chronic and multiple traumatization. Methodological limitations restricting causal inferences between reported trauma and dissociation are discussed.

Adolescent↗

PubMed1995

Dissociation and vulnerability to psychotic experience. The Dissociative Experiences Scale and the MMPI-2.

Prior research on the MMPI has cautioned against misdiagnosing schizophrenia in patients with dissociative identity disorder. The present study examined the full spectrum of the dissociative experience in relation to MMPI-2 profiles. Ninety-eight women in treatment for trauma-related disorders completed the Dissociative Experiences Scale and the MMPI-2 in routine inpatient diagnostic evaluations. Consistent with prior research, severe dissociation was associated with high elevations on MMPI-2 scales typically associated with psychotic symptoms. Contrary to hypotheses, the ostensibly most benign form of dissociation, absorption and imaginative involvement, was somewhat more strongly related to MMPI-2 scores than the more pathognomonic forms of dissociation, depersonalization and amnesia. Although it should not be misdiagnosed, severe impairment on the MMPI in conjunction with dissociation should be taken seriously as suggesting vulnerability to psychotic experience. The dissociative retreat from the stressors of outer reality opens the door to the inner world of traumatic images and affects, along with compromised reality testing and disorganized thinking.

Adult↗

PubMed2002

Comparison of the collision-induced dissociation of duplex DNA at different collision regimes: evidence for a multistep dissociation mechanism.

The dissociation mechanism of duplex DNA has been investigated in detail by collision-induced dissociation experiments at different collision regimes. MS/MS experiments were performed either in a quadrupole collision cell (hybrid quadrupole-TOF instrument) or in a quadrupole ion trap with different activation times and energies. In addition to the noncovalent dissociation of the duplex into the single strands, other covalent bond fragmentation channels were observed. Neutral base loss from the duplex is favored by slow activation. In fast activation conditions, however, the major reaction channel is the noncovalent dissociation into single strands, which is highly entropy-favored. Fast activation regimes can favor the entropy-driven noncovalent dissociation, while in slow heating conditions the competition with enthalpy-driven covalent fragmentation can completely hinder the dissociation of the complex. We also evidence that the noncovalent dissociation of DNA duplex is a multistep process involving a progressive unzipping, preferentially at terminal positions. This is proposed to be a general feature for complexes containing a high number of contributing interactions organized at the interface of the ligands. The overall (observed) dissociation kinetics of noncovalent complexes can therefore depend on a complicated mechanism for which a single transition state description of the kinetics is too simplistic.

Binding, Competitive↗

PubMed1984

Kinetics and mechanism of dissociation of cooperatively bound T4 gene 32 protein-single-stranded nucleic acid complexes. 1. Irreversible dissociation induced by sodium chloride concentration jumps.

The dissociation kinetics of cooperatively bound bacteriophage T4 gene 32 protein from a variety of single-stranded homopolynucleotides has been investigated by stopped-flow techniques. Irreversible dissociation of the complexes was induced by rapidly increasing the salt concentration and monitoring the increase in tryptophan fluorescence upon dissociation of the gene 32 protein. The dependence of the apparent dissociation rate constant on initial fractional saturation of the nucleic acid lattice as well as the observation of zero-order kinetics when the lattice is initially fully saturated with protein indicates that dissociation occurs only from the ends of protein clusters and not from doubly contiguous molecules. The data for the entire time course are quantitatively fit by a kinetics model specifying irreversible dissociation of only singly contiguously bound protein [Lohman, T.M. (1983) Biopolymers 22, 1697-1713]. This model is used to extract molecular rate constants for the dissociation of isolated, singly contiguously and doubly contiguously bound protein. It is also shown that the polynucleotide specificity observed for the cooperative binding constant, K omega, and the cooperativity itself are intrinsic properties of the dissociation rate of the various complexes.

DNA, Single-Stranded↗

PubMed1989

Anomalous pressure dissociation of large protein aggregates. Lack of concentration dependence and irreversibility at extreme degrees of dissociation of extracellular hemoglobin.

The effects of hydrostatic pressure on the extracellular hemoglobin of Glossoscolex paulistus were investigated by studies of light scattering, intrinsic protein fluorescence, filtration chromatography, and oxygen binding. Pressure promoted a large decrease of light scattering consistent with the dissociation of the hemoglobin. Pressures up to 1.7 kbar caused dissociation with reversibility of the light scattering and fluorescence properties after return to atmospheric pressure. Higher pressures provoked additional dissociation with increasing loss of reversibility. After complete dissociation by incubation at 2.5 kbar followed by decompression, the protein continued mostly dissociated. The dissociated forms were distributed in two populations as based on size exclusion chromatography, one corresponding to small dissociated units (average Mr = 33,000) and the other population corresponding to the one-twelfth subunit (260,000 Mr). The pressure dissociation curves showed no significant dependence on protein concentration suggesting that the native hemoglobin population exists in a distribution of free-energies of association. Both the decrease of concentration dependence and the loss of ability to reassemble seem to increase with the complexity and size of the protein aggregate. These findings permit the conclusion that increased heterogeneity of free-energies of association with the size of the aggregate may result in the molecular individuality of large protein complexes such as subcellular particles and viruses.

Animals↗

PubMed1994

Distinguishing between multiple personality disorder (dissociative identity disorder) and schizophrenia using the Structured Clinical Interview for DSM-IV Dissociative Disorders.

The authors describe the systematic assessment of dissociative symptoms using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D) in 50 psychiatric outpatients with a referring DSM-III-R diagnosis of either schizophrenia or schizoaffective disorder (N = 31) and subjects with multiple personality disorder (MPD [DSM-IV name change: dissociative identity disorder]; N = 19). Results indicate that patients with MPD experience significantly higher scores for five specific dissociative symptoms than patients with schizophrenia or schizoaffective disorder. The range, severity, and nature of the five dissociative symptom areas evaluated by the SCID-D distinguish MPD from the occasional occurrence of dissociative symptoms which may be seen in schizophrenia. Systematic assessment of dissociative symptoms using the SCID-D can assist in accurate differential diagnosis of MPD and schizophrenia.

Adult↗