Performance of a miniaturised O2−Hb dissociation curve analyser on dog's blood

Oxygen-haemoglobin dissociation curves were determined on dogs' blood using a modified and miniaturised dissociation curve analyser. The Bohr factor describes the way in which pH varies the PO₂ corresponding to a particular oxyhaemoglobin concentration. The factor was similar for three saturations and was little affected by whether the pH was changed by changing PCO₂, or by adding fixed acid or alkali. The haemoglobin saturations in the mid-range tended to be lower than those predicted by the equation of Rossing and Cain (1966)     

The high affinity peripheral benzodiazepine receptor ligand DAA1106 binds specifically to microglia in a rat model of traumatic brain injury: implications for PET imaging

Traumatic brain injury (TBI) is a significant cause of mortality, morbidity, and disability. Microglial activation is commonly observed in response to neuronal injury which, when prolonged, is thought to be detrimental to neuronal survival. Activated microglia can be labeled using PK11195, a ligand that binds the peripheral benzodiazepine receptor (PBR), receptors which are increased in activated microglia and sparse in the resting brain. We compared the binding properties of two PBR ligands PK11195 and DAA1106 in rats using the controlled cortical impact (CCI) model of experimental TBI. While both ligands showed relative increases with specific binding in the cortex ipsilateral to injury compared to the contralateral side, [(3)H]DAA1106 showed higher binding affinity compared with [(3)H](R)-PK11195. Combined immunohistochemistry and autoradiography in brain tissues near the injury site showed that [(3)H]DAA1106 binding co-registered with activated microglia more than astrocytes. Further, increased [(3)H]DAA1106-specific binding positively correlated with the degree of microglial activation, and to a lesser degree with reactive astrocytosis. Finally, in vivo administration of each ligand in rats with TBI showed greater retention of [(11)C]DAA1106 compared to [(11)C](R)-PK11195 at the site of the contusion as assessed by ex vivo autoradiography. These results in a rat model of TBI indicate that [(11)C]DAA1106 binds with higher affinity to microglia when compared with PK11195, suggesting that [(11)C]DAA1106 may represent a better ligand than [(11)C](R)-PK11195 for in vivo PET imaging of activated microglia in TBI.     

Ataque de nervios: relationship to anxiety sensitivity and dissociation predisposition

We investigated the relative importance of "fear of arousal symptoms" (i.e., anxiety sensitivity) and "dissociation tendency" in generating ataque de nervios. Puerto Rican patients attending an outpatient psychiatric clinic were assessed for ataque de nervios frequency in the previous month, and they completed the Anxiety Sensitivity Index (ASI) and the Dissociation Experiences Scale (DES). ASI scores were especially high in the ataque-positive group (M=41.6, SD=12.8) as compared with the ataque-negative group (M=27.2, SD=11.7), t(2, 68)=4.6, P<.001. Among the whole sample (N=70), in a logistic regression analysis, the ASI significantly predicted (odds ratio=2.6) the presence of ataque de nervios, but the DES did not. In a linear regression analysis, ataque severity was significantly predicted by both the ASI (beta=.46) and the DES (beta=.29). The theoretical and clinical implications of the strong relationship of the ASI to ataque severity are discussed.     

Comparison of two types of dissociation in epileptic and nonepileptic seizures

Dissociation is regarded as a possible psychological mechanism in nonepileptic seizures (NES), although existing evidence for this is equivocal. It has been suggested that the contradictory findings in this area reflect the use of measures that conflate qualitatively distinct types of dissociation, and provide inadequate coverage of the aspects of dissociation most closely related to NES. The study described here addressed this shortcoming by measuring the occurrence of two different types of dissociation, “detachment” (measured using the Cambridge Depersonalisation Scale) and “compartmentalization” (measured using the Somatoform Dissociation Questionnaire), in patients with NES (n = 32) and epilepsy controls (n = 37). As predicted, patients with NES scored significantly higher on the measure of compartmentalization only; contrary to prediction, however, this difference was no longer significant when anxiety and depression were controlled for. The conceptual and methodological implications of the study are discussed.     

Childhood trauma and dissociation in women with pseudoseizure-type conversion disorder

Background: Conversion disorder is thought to be associated with psychological factors because of the presence of conflict and other stressors prior to the condition. Aim: The aim of this study is to compare adult patients with pseudoseizure-type conversion disorder with healthy control group in terms of childhood trauma, dissociative disorder and family history of psychiatric disorders. Method: 56 female patients were admitted to the general psychiatry hospital outpatient clinic between January and July 2005. All patients had a negative experience about their families just before having the conversion. Diagnosis was made according to the DSM-IV criteria. A control group consisting of similar patient demographics of the disease group has been selected. Socio-demographic information forms, the Childhood Trauma Questionnaire (CTQ) and Dissociation Questionnaire (DIS-Q), were completed on the patients. Results: CTQ total (t=12.12, P<0.001) and subscales, emotional abuse and emotional neglect (EA-EN) (t=12.74, P<0.001), physical abuse (PA) (t=10.05, P<0.001), and sexual abuse (SA) (t=7.69, P<0.001) were significantly high in the conversion group. DIS-Q mean points were statistically higher in the conversion group (t=11.05, P<0.001). Conclusions: The findings suggest that pseudoseizures (conversion disorder) should be included within dissociative disorders in DSM system as in ICD. It is usually uncommon for the patient to tell about childhood trauma without being specially questioned about this issue. Thus, it would be helpful to uncover these experiences by using related scales in conversion disorder patients.     

On the Dimensionalities of the Dissociative Experiences Scale (DES) and the Dissociation Questionnaire (DIS-Q)

Abstract

The dimensionalities of the Dissociative Experiences Scale (DES) and the Dissociation Questionnaire (DIS-Q) have been explored by factor analysis by a number of investigators. The general claim is that both scales are multidimensional. However, we argue that, in both cases, this ap parent multidimensionality is a form of range restriction that arises because some symptoms are more common than other symptoms. As a result, the resulting subscales derived from the multifactor solutions are so highly intercorrelated as to be incapable of meaningful discriminant validity. The current findings support a more parsimonious single factor solution for both scales.     

Case report: Improvement in dissociative symptoms with mixed amphetamine salts

Symptoms of dissociation, including dissociative amnesia, depersonalization, and derealization, commonly develop in individuals subject to chronic and repeated trauma during development. This includes the trauma of environmental inability to facilitate development of adequate cognitive strategies for coping with strong negative emotions. Dissociation likely involves dysregulated balance of prefrontal inhibition of limbic structures and inadequate regulation of attentional bias by both prefrontal and limbic systems. There is currently no established psychopharmacologic treatment for dissociative symptoms. Here the case of a woman with severe dissociative symptoms that were markedly improved with the administration of mixed amphetamine salts is discussed. Potential neurobiologic mechanisms for dissociative symptom improvement with psychostimulants are discussed.     

Experiences of therapeutic relationships on hospital wards,dissociation, and making connections

An interpretive phenomenological analysis sought to explore how people reporting moderate to high levels of dissociation experienced relationships with multidisciplinary hospital ward staff. Three superordinate themes were developed. First, the theme “multiple me and multiple them” explores the instability experienced by the participants as they managed their dissociative experiences alongside many inconsistencies. Second, “recognizing, meeting, or neglecting interpersonal and care needs” reflects on participants’ needs within therapeutic relationships. Third, “between the needs of the internal system: navigating between ‘better on my own’ and ‘someone to talk to’” discusses the confusion and understanding around dissociation and the importance of working with parts, not around them. Findings suggested that the current culture of some hospital wards directly influenced participants’ distress, which could lead to further dissociation as a means of coping with perceived threats. Reflections on relational complexities and developing ward-based treatment are discussed.