Objectives: The relationship between dissociation and PTSS was studied by examining the moderating role of prior trauma. The relationship between prior trauma and PTSS was studied by examining the mediating role of dissociation. The relationship between various coping styles, dissociation and prior trauma was also addressed. Study Design: The current study was a retrospective correlational between-subjects design. Subjects: The study included 90 subjects who were admitted into a level one trauma center following a traumatic physical injury. Results: Dissociation was most strongly and significantly related to PTSS (r = .583). Childhood sexual abuse, childhood physical abuse, and total prior trauma were also significantly related to PTSS (r = .249, r =.298, r = .295, respectively). The results of the study indicated that prior trauma did not moderate the relationship between dissociation and PTSS. The addition of the interaction term (prior trauma X dissociation) explained 3.5% additional variance in PTSS (F(3,82) = 1.10, p = .354). However, the relationship between prior trauma and PTSS was found to be partially mediated by dissociation. The effect of prior trauma on PTSS was reduced when dissociation was added into the regression equations for each of the prior trauma predictor variables including: childhood sexual abuse (b = 9.122 reduced to b = 2.050), childhood physical abuse (b = 1.011 reduced to b = .547), and total prior trauma (b = .114 reduced to b = .055). Dissociation was also found to be significantly related to maladaptive coping including: emotional venting (r = .373), denial (r = .213), and behavioral disengagement (r = .330). Prior trauma was not found to be related to maladaptive coping styles. Conclusions: The study findings suggest that the relationship between prior trauma and PTSS is partially due to the engagement in dissociation. However, those who have not experienced a prior trauma are also at risk for experiencing dissociation and subsequent PTSS. Additionally, dissociation was found to be related to maladaptive coping, while prior trauma was not significantly related to any coping styles. Therefore, the findings suggest that dissociation is related to more disruptive psychological sequelae, as compared to pre-trauma factors such as the experience of prior trauma.

A Matrix-assisted Laser Desorption/Ionization (MALDI) – Ion Mobility (IM) – Surface-induced Dissociation (SID) – Time-of-Flight (TOF) instrument with three different collision source configurations was developed in order to improve the SID performance in high throughput peptide sequencing. The first version of the instrument was equipped with an angle resolved SID source in order to maximize the collection efficiency of the SID scattering ions. An orthogonal TOF was also implemented as the second MS stage in this instrument to increase mass resolution. The second version of the instrument was developed towards simplifying the coupled configuration of the IM, SID and TOF components by using a combined SID/TOF source with a confinement ring electrode as the collision target. The fragmentation efficiency of SID in this configuration was increased up to 50% due to the surface normal impact angle used as compared with the results from a previous experiment using 45 degree impact angle. The third version of the instrument was equipped with a dual-source/dual-detector TOF to facilitate high throughput tandem analysis of peptides through simultaneous separation, fragmentation and mass analysis, while retaining precursor ion identity in the same experimental sequence. A series of small organic molecules, model peptides and tryptic peptides from a protein digest were analyzed to demonstrate the utility of these new designs for enhanced SID performance and peptide sequencing capability. Finally, a new mobility drift cell using a periodic focusing mechanism has been designed and fabricated to replace the previous uniform field drift cell. Improvement in ion transmission has been observed in the periodic focusing drift cell instrument without sacrificing the mobility resolution.

A Matrix-assisted Laser Desorption/Ionization (MALDI) – Ion Mobility (IM) – Surface-induced Dissociation (SID) – Time-of-Flight (TOF) instrument with three different collision source configurations was developed in order to improve the SID performance in high throughput peptide sequencing. The first version of the instrument was equipped with an angle resolved SID source in order to maximize the collection efficiency of the SID scattering ions. An orthogonal TOF was also implemented as the second MS stage in this instrument to increase mass resolution. The second version of the instrument was developed towards simplifying the coupled configuration of the IM, SID and TOF components by using a combined SID/TOF source with a confinement ring electrode as the collision target. The fragmentation efficiency of SID in this configuration was increased up to 50% due to the surface normal impact angle used as compared with the results from a previous experiment using 45 degree impact angle. The third version of the instrument was equipped with a dual-source/dual-detector TOF to facilitate high throughput tandem analysis of peptides through simultaneous separation, fragmentation and mass analysis, while retaining precursor ion identity in the same experimental sequence. A series of small organic molecules, model peptides and tryptic peptides from a protein digest were analyzed to demonstrate the utility of these new designs for enhanced SID performance and peptide sequencing capability. Finally, a new mobility drift cell using a periodic focusing mechanism has been designed and fabricated to replace the previous uniform field drift cell. Improvement in ion transmission has been observed in the periodic focusing drift cell instrument without sacrificing the mobility resolution.

The number and types of diagnostic ions obtained by infrared multiphoton dissociation (IRMPD) and collision induced dissociation (CID) were evaluated for supercharged peptide ions created by electrospray ionization of solutions spiked with mnitrobenzyl alcohol. IRMPD of supercharged peptide ions increased the sequence coverage compared to that obtained by CID for all charge states investigated. Multiply charged, N-terminally derivatized peptides were subjected to electron transfer reactions to produce singly charged, radical species. Upon subsequent “soft” CID, highly abundant z-type ions were formed nearly exclusively, which yielded simplified fragmentation patterns amenable to de novo sequencing methods. Furthermore, the simplified series of z ions were shown to retain labile phosphoric acid moieties. Infrared multiphoton dissociation (IRMPD) was implemented in a novel dual pressure linear ion trap for rapid “top-down” proteomics. Due to secondary dissociation, IRMPD yielded product ions in significantly lower charge states as compared to CID, thus facilitating more accurate mass identification and streamlining product ion assignment. This outcome was especially useful for database searching of larger proteins (~29 kDa) as IRMPD substantially improved protein identification and scoring confidence. Also, IRMPD showed an increased selectivity towards backbone cleavages N-terminal to proline and C-terminal to acidic residues (especially for the lowest precursor charge states). Ultraviolet photodissociation (UVPD) at 193 nm was implemented on a linear ion trap mass spectrometer for high-throughput proteomic workflows. Upon irradiation by a single 5 ns laser pulse, efficient photodissociation of tryptic peptides was achieved with production of a, b, c, x, y, and z sequence ions, in addition to immonium ions and v and w side-chain loss ions. The factors that influence the UVPD mass spectra and subsequent in silico database searching via SEQUEST were evaluated. 193 nm ultraviolet photodissociation (UVPD) was employed to sequence singly and multiply charged peptide anions. Upon dissociation by this method, a-/x-type, followed by d and w side-chain loss ions, were the most prolific and abundant sequence ions, often yielding 100% sequence coverage. LC-MS/UVPD analysis using high pH mobile phases yielded efficient characterization of acidic peptides from mitogen-activated protein kinases. / text

Background: Differential relationships of the dimensions of psychopathy with external factors indicate that psychopathy can be conceptualised as a multifaceted syndrome comprised of distinct subgroups of psychopaths (Blackburn, 1988). However, it is not known whether similar subtypes of psychopathy exist across cultures. The research question which this thesis sought to answer was: Do subtypes of psychopathy exist among murderers, and if so, might the prevalence of these subtypes differ across cultures? Three aims were addressed: i) to compare the trauma histories, dissociative experiences and psychopathic features of British and South African men convicted of murder and the associations among them; ii) to test potential aetiological models of psychopathy; and iii) to explore whether subtypes of psychopathy could be identified among men convicted of murder. Method: Participants were 120 adult male prisoners serving sentences for murder. Sixty participants were British and incarcerated in prisons in England and 60 participants were South African and incarcerated in South Africa. Trauma, dissociation and psychopathy were measured using the Trauma History Questionnaire (THQ; Green, 1996), the Dissociative Experiences Scale (DES; Carlson & Putnam, 1993) and the Psychopathy Checklist-Revised Second Edition (PCL-R; Hare, 2003a), respectively. Results: South African participants reported significantly more traumatic and dissociative experiences and possessed more psychopathic features than their British counterparts. Structural equation modelling (SEM) analyses of the entire sample revealed that trauma was positively and directly related to the behavioural features of psychopathy, whereas trauma was positively and indirectly related to the affective features of psychopathy via the partial mediating role of dissociation, suggesting that subtypes of psychopathy may exist among murderers. In addition, cluster analyses identified subtypes of psychopathy, two of which parallel variants of primary and secondary psychopathy described in the literature. Conclusions: Dissociation may mediate the relationship between trauma and psychopathy among individuals who have experienced high levels of trauma, suggesting that there may be a threshold or a ‘cut-off’ level at which witnessing or experiencing trauma becomes detrimental for one’s psychological health. The prevalence of certain subtypes of psychopathy may differ across cultures. Findings have theoretical implications as well as implications for the treatment and risk assessment of offenders.

During traumatic events, individuals can experience dissociative symptoms related to changes in cognitively processing; these changes are suggested to impact on the development of posttraumatic stress disorder (PTSD) symptoms. Past literature has proposed two forms of peritraumatic dissociation (compartmentalisation and detachment), however little quantitative research has focussed on separately manipulating these experiences in order to further our understanding of their aetiology. The current study addressed this knowledge gap and additionally sought to understand the role of cognitive processing in the dissociation-intrusion relationship. Using an audio-only adaption of the trauma film paradigm, 60 participants were divided into three conditions and presented with different visual tasks - mirror staring, dot-staring or neutral images – that were hypothesised to induce the two forms of dissociation. Post-audio, a number of factors were assessed, including state dissociation, perceptual priming and conceptual priming, as well as intrusions over the following days. As hypothesised, participants in the dissociation conditions displayed an increase in perceptual priming compared the control conditions, and reported more severe intrusions. However, no differences were found in conceptual priming, in the overall number of intrusions between conditions, or in dissociative symptoms between the dissociation conditions. The current study utilised new techniques in the analysis of PTSD and its origins, and showed their potential in the experimental study of dissociation and analogue trauma techniques. The findings also contributed to the growing body of knowledge investigating the impact that dissociation and cognitive processing has on the aetiology of PTSD.

Mass spectrometry has become an important tool for analysis of protein complexes. This study utilizes electrospray ionization (ESI) coupled to a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) to analyze noncovalent complexes in the gas phase. Binding of cucurbit[7]uril (CB7) to intact bovine insulin and the B-chain of insulin was investigated. Competition experiments involving the B-chain and a mutant B-chain were performed to probe the solution-phase binding site. Electron capture dissociation (ECD) of CB7 complexed to intact insulin and to the B-chain, produced a series of peptidic fragments of insulin in complex with CB7. Analysis of these fragments allowed the determination of the apparent gas-phase binding site, which appears different than the proposed solution-phase binding-site. These studies thus suggest that CB7 migrates when the complex is transferred from solution to gas phase. The results of this study caution against using ECD-MS as a stand-alone structural probe of solutionphase binding.

Mass spectrometry has become an important tool for analysis of protein complexes. This study utilizes electrospray ionization (ESI) coupled to a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) to analyze noncovalent complexes in the gas phase. Binding of cucurbit[7]uril (CB7) to intact bovine insulin and the B-chain of insulin was investigated. Competition experiments involving the B-chain and a mutant B-chain were performed to probe the solution-phase binding site. Electron capture dissociation (ECD) of CB7 complexed to intact insulin and to the B-chain, produced a series of peptidic fragments of insulin in complex with CB7. Analysis of these fragments allowed the determination of the apparent gas-phase binding site, which appears different than the proposed solution-phase binding-site. These studies thus suggest that CB7 migrates when the complex is transferred from solution to gas phase. The results of this study caution against using ECD-MS as a stand-alone structural probe of solutionphase binding.

Dissociation may be broadly described as a subjective experience in which information from the individual's internal or external environment is not appropriately integrated into conscious awareness, memory or identity. A number of studies have found an association between dissociative experience and anxious arousal, and in particular, between dissociation and trauma. Recent reviews suggest the existence of an unspecified mediating variable that accounts for these associations. The present study compared dissociative experiences reported by a community sample (N = 74) and a sample of individuals with a range of anxiety disorders (N = 20). The potential influence of anxiety sensitivity was a particular focus. Participants completed a battery of measures assessing dissociative experience, anxious arousal, social anxiety, generalised anxiety, panic and agoraphobia, traumatic experience and posttraumatic stress in addition to measures of anxiety sensitivity and substance use. Participants in the anxiety group reported a greater variety and frequency of dissociative experiences, particularly of experiences considered to be pathological in nature. Elevated dissociation scores were associated with somatic symptoms of anxiety, social anxiety, generalised anxiety, agoraphobia and posttraumatic stress. No association between trauma exposure and dissociation was evident; however, trauma intensity was associated with dissociation in the anxiety group. Symptoms of depersonalisation / derealisation and absorption were most strongly associated with increased anxiety. Anxiety Sensitivity accounted for more of the variance in dissociation scores than did measures of expressed anxiety. These results suggest that anxiety sensitivity may account for the relationship between trauma anxiety and dissociation. Therapeutic intervention directed at anxiety sensitivity, particularly fear of cognitive discontrol, may prove helpful in treating dissociative detachment.

Thesis (Ph. D.)--University of Pennsylvania, 1934. / "Reprint from the Journal of physical chemistry, vol. 39, no. 4, and no. 6, 1935." "References: " p. 13, 23.