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Biomedical subjects

D A Oakley

Publications and source records attributed to D A Oakley.

At least 19 recordsLinked to original sources
PubMed2003

Delusions of alien control in the normal brain.

Delusions of alien control, or passivity experiences, are symptoms associated with schizophrenia in which patients misattribute self-generated actions to an external source. In this study hypnosis was used to induce a similar misattribution of self-generated movement in normal, healthy individuals. Positron Emission Tomography (PET) was employed to investigate the neural correlates of active movements correctly attributed to the self, compared with identical active movements misattributed to an external source. Active movements attributed to an external source resulted in significantly higher activations in the parietal cortex and cerebellum than identical active movements correctly attributed to the self. We suggest that, as a result of hypnotic suggestion, the functioning of this cerebellar-parietal network is altered so that self-produced actions are experienced as being external. These results have implications for the brain mechanisms underlying delusions of control, which may be associated with overactivation of the cerebellar-parietal network.

Adult↗
PubMed2003

Differential brain activations during intentionally simulated and subjectively experienced paralysis.

INTRODUCTION: Distinguishing conversion disorder from malingering presents a significant challenge as the diagnosis ultimately depends on the patient's subjective report and the clinician's suspicion of an intention to deceive. Using hypnosis to manipulate the intentionality of movement inhibition in the same subjects, we used positron emission tomography (PET) to determine whether failure to move during intentionally simulated and subjectively experienced paralysis is mediated by different neural structures. METHODS: Using a within-subject design, 12 normal, hypnotised subjects were tested under two paralysis conditions during the same scanning session. Half of the scans were performed with the suggestion that the left leg was paralysed (subjectively experienced paralysis condition) and half with the leg normal but with the instruction that paralysis should be feigned (intentionally simulated paralysis condition). RESULTS: Relative increases in brain activation were seen in the right orbitofrontal cortex, right cerebellum, left thalamus, and left putamen during subjectively experienced paralysis compared to intentionally simulated paralysis, although a previously reported activation of the right anterior cingulate cortex was not seen. During intentionally simulated paralysis compared to subjectively experienced paralysis relative increases in brain activation were seen in the left ventrolateral prefrontal cortex, and a number of right posterior cortical structures. CONCLUSIONS: Our results suggest that subjectively experienced paralysis has a different neural basis to intentionally simulated paralysis. These findings have theoretical and clinical implications for malingering and related attempts to unravel the neuropsychological basis for conversion hysteria.

Journal Article↗
PubMed2001

Transmission of visceral leishmaniasis through blood transfusions from infected English foxhounds to anemic dogs.

OBJECTIVE: To conduct serologic surveillance for Leishmania spp in English foxhounds from a kennel, as well as recipients of blood from these dogs, and determine whether L infantum organisms could be transmitted via blood transfusion. DESIGN: Serologic prevalence survey. ANIMALS: 120 English foxhounds and 51 dogs of various breeds receiving blood from these donors. PROCEDURE: Foxhound blood donors, foxhound nondonors, and nonfoxhound blood recipient dogs were evaluated serologically for Leishmania spp by indirect fluorescent antibody testing. Dogs that received packed RBC (PRBC) transfusions from foxhound donors from mid-1996 through mid-2000 were identified. Furthermore, dogs were serologically evaluated if they had received fresh frozen plasma (FFP) transfusions in 1999 and 2000 from seropositive foxhound blood donors. RESULTS: Thirty percent of the English Foxhounds were seropositive for Leishmania spp (titer > or = 1:16), although the degree of seropositivity varied considerably during the period. Furthermore, 57 foxhounds had been used as donors from 1996 to 2000, and 342 units of PRBC had been transfused to at least 227 patients. All 25 dogs screened that received PRBC from seronegative foxhound donors tested negative, whereas 3 of 7 dogs that received PRBC from seropositive donors tested positive. All 9 dogs that received FFP from seropositive foxhound donors remained seronegative. CONCLUSIONS AND CLINICAL RELEVANCE: To our knowledge, this report documents the first transmission of Leishmania spp by blood transfusion. The use of foxhounds as blood donors may not be advisable in North America.

Anemia↗
PubMed2001

Clinical indications for use of fresh frozen plasma in dogs: 74 dogs (October through December 1999).

OBJECTIVE: To document reasons for use of fresh frozen plasma (FFP) in dogs and determine variables that apparently triggered the decision to use FFP. DESIGN: Retrospective study. ANIMALS: 74 dogs. PROCEDURE: Medical records of dogs that received FFP at a veterinary teaching hospital during a 3-month period were reviewed. RESULTS: The 74 dogs underwent 144 transfusion episodes (TE; a TE was defined as 1 day of transfusion therapy) and received 252 units (120 ml/unit) of FFP. Fresh frozen plasma was administered to provide coagulation factors (67 TE), albumin (91), alpha-macroglobulin (15), or immunoglobulins (19); for some TE, multiple clinical indications were identified. Variables that apparently triggered the decision to administer FFP included active hemorrhage with or without prolongation of coagulation times, low total plasma protein concentration, persistent vomiting associated with pancreatitis, and sepsis. Mean doses of FFP for each indication were between 8.5 and 9.4 ml/kg (3.9 and 4.3 ml/lb). Small dogs were generally given higher doses (mean dose, 13.9 ml/kg [6.3 ml/lb]) than large dogs (mean dose, 5.1 ml/kg [2.3 ml/lb]). Fifty (68%) dogs were alive at the time of discharge from the hospital. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that FFP plays an important role in the care of critically ill dogs. Because the supply of FFP is limited, guidelines for when administration of FFP may be clinically useful should be developed.

Animals↗
PubMed2000

Imaging hypnotic paralysis: implications for conversion hysteria.

In a single case study with positron emission tomography (PET) functional imaging, hypnotic paralysis activated similar brain areas to those in conversion hysteria, supporting the view that hypnosis and hysteria might share common neurophysiological mechanisms.

Adult↗
PubMed2000

Dissociation, hypnotizability, coping styles and health locus of control: characteristics of pseudoseizure patients.

Although literature in this area is relatively sparse, the occurrence of psychogenic non-epileptic seizures (pseudoseizures) has been linked to stress, anxiety and possible dissociative tendencies. An association between dissociation and hypnotic susceptibility has also been proposed and dissociative tendencies have themselves been found to relate to the use of emotion-focused coping strategies. In order to investigate the hypothesis that pseudoseizure patients may exhibit higher levels of dissociation, a more emotion-focused coping style, and greater hypnotic susceptibility than the general population, the questionnaire responses of 20 patients with pseudoseizures were compared with those obtained from a non-clinical control group. As predicted, pseudoseizure patients demonstrated some evidence of higher levels of dissociation and escape-avoidance coping strategies. They also expressed a greater belief in external control over health and higher depression scores, compared to the control group, but the previously reported elevation in hypnotizability scores in the pseudoseizure patients was not found. Possible explanations for this pattern of results are discussed.

Adaptation, Psychological↗
PubMed1999

Hypnosis and conversion hysteria: a unifying model.

There are many similarities between the symptoms of conversion hysteria and phenomena produced in hypnotic contexts. This paper reviews some of those similarities and considers more general features associated with both hypnotic phenomena and conversion hysteria symptoms such as lack of concern, perceived involuntariness, the display of ''implicit knowledge'' and their apparently compliant nature. Neurophysiological and brain-imaging studies of hypnotically produced effects and conversion symptoms are described, which implicate frontal cortical structures in moderating the respective changes elsewhere in the brain, particularly in cingulate cortex. A recurrent theme is the apparent paradox which exists between, on the one hand, the subjective reality and involuntariness of both hypnotic phenomena and the symptoms of conversion hysteria and, on the other, the fact that objectively they appear to be role-congruent enactments responsive to the manipulation of motivational factors, expectancy, and social influence. A model of consciousness and self-awareness is presented which attempts to resolve that paradox whilst describing similar mechanisms underlying hypnotic phenomena and conversion hysteria symptoms. The model develops the idea of a central executive structure, similar to the notion of a supervisory attentional system, acting outside self-awareness but at a late stage of information processing which can be directly influenced from both internal and external sources to produce the relevant phenomena. The paper ends by proposing that as conversion disorder, pain disorder, and the dissociation disorders appear to be linked by a common mechanism they should be classified together under the heading of auto-suggestive disorder.

Journal Article↗
PubMed1998

Psychosocial factors, dental plaque levels and smoking in periodontitis patients.

Psychological disturbances may lead patients to neglect oral hygiene. This study investigated whether a number of psychosocial factors (depression, state and trait anxiety, total and average perceived stress, and loneliness) could predict dental plaque levels in patients with adult onset rapidly progressive periodontitis (RPP) and routine chronic adult periodontitis (RCAP), before periodontal treatment. It was also examined whether RPP and RCAP patients differed on plaque and smoking. Plaque was scored in a sample of 6 teeth in each of 80 subjects, 40 with RPP, 40 with RCAP, before psychosocial questionnaire completion. Multiple regression was performed between plaque as the dependent and psychosocial factors, gender, education, form of periodontitis and smoking as independent variables. Only gender contributed significantly to prediction of plaque, t=-2.70, p=0.01, partial regression coefficient -0.37, 95% CI: -0.64 to -0.10, indicating that plaque was on average 0.37 lower for females than males, after adjusting for the other predictor variables. It was confirmed that RPP and RCAP patients did not differ significantly on plaque, univariate t-test(69.99)= 0.65, p=0.13. However, RPP patients smoked significantly more than RCAP patients t(69.72)=2.36, p=0.02. There was also a marginally significant correlation between depression and smoking, r=0.16, p=0.07. One possible reason advanced for the lack of an association between psychosocial factors and plaque, and the absence of a difference in plaque between RPP and RCAP patients is the fact that the patients involved in the present study were seen as secondary referrals. The gender difference in plaque levels and the greater incidence of smoking in RPP patients may be of significance in planning interventions with patients with periodontitis.

Adult↗
PubMed1997

Psychosocial factors and tooth wear with a significant component of attrition.

Pathological tooth wear is often associated with bruxism, which appears in turn to be influenced by psychosocial factors. This study investigated putative relationships between psychosocial factors (total and average perceived stress, state and trait anxiety) and tooth wear, comparing 45 patients exhibiting tooth wear with a significant component of attrition to 45 controls. Groups were matched for gender and age. Subjects completed the Modified and Perceived Stress Scale and the State-Trait Anxiety Inventory. A between-groups multivariate analysis of variance indicated that the two groups did not differ significantly on the combined psychosocial factors, F(4,85) = 1.16, P > 0.05. However, a univariate F-test showed that tooth-wear patients presented significantly more trait anxiety than controls, F(1,88) = 4.15, P < 0.05. Further research is indicated to clarify the importance of trait anxiety and other psychosocial factors in the progression of tooth wear with a significant component of attrition.

Adult↗
PubMed1996

Psychosocial factors and adult onset rapidly progressive periodontitis.

On the basis of clinical observations, some periodontologists have suggested an association between psychosocial factors such as depression, stress and anxiety, and adult onset rapidly progressive periodontitis (RPP). This study investigated more formally possible associations between a number of relevant psychosocial factors and RPP. The significance of the psychosocial variables was assessed by comparing 3 groups: 50 patients with RPP, 50 patients with routine chronic adult periodontitis (RCAP), and 50 patients without significant periodontal destruction (controls). It was anticipated that the RPP group would show higher levels of psychosocial maladjustment than the RCAP and control groups. A between-subjects multivariate analysis of covariance indicated that the combined psychosocial variables were significantly related to the periodontal diagnosis. 2 psychosocial factors, depression and loneliness, were significant in distinguishing between groups. The RPP group presented significantly increased depression and loneliness compared to the RCAP and control groups. Future research is indicated to further clarify the significance of these psychosocial differences in relation to the onset and progression of RPP.

Acute Disease↗
PubMed1995

An acute hemolytic transfusion reaction caused by dog erythrocyte antigen 1.1 incompatibility in a previously sensitized dog.

An acute hemolytic transfusion reaction resulting from dog erythrocyte antigen (DEA) 1.1 incompatibility developed in a dog previously sensitized to DEA 1.1 by a transfusion 3 years earlier. The dog developed fever, pigmenturia, and lethargy, and its PCV did not rise as expected. The donor blood was type DEA 1.1 positive, whereas the recipient's blood was type DEA 1.1, DEA 1.2, and DEA 7 negative. A major crossmatch was later found to be strongly incompatible. Studies of the recipient's plasma revealed a specific anti-DEA 1.1 alloantibody of the IgG class with high hemolysin and agglutinin activity. Such acute hemolytic transfusion reactions can be avoided by crossmatching previously transfused dogs and by using dogs that are type DEA 1.1 negative (and preferably also type DEA 1.2 and DEA 7 negative) as blood donors.

Acute Disease↗
PubMed1995

Psychosocial factors in inflammatory periodontal diseases. A review.

Reviewing the literature concerning the possible rôle of psychosocial factors in the aetiology of inflammatory periodontal diseases, it may be concluded that there is evidence which strongly suggests that emotional stress is one of the predisposing factors to ANUG. On the other hand, it is not clear that the scientific evidence is sufficient to substantiate the hypothesis that psychosocial factors are of aetiological importance in periodontitis. The proposed mechanisms which may mediate the putative relationship between psychosocial conditions and inflammatory periodontal diseases remain to be tested. However, psychoneuroimmunologic studies make lowered host resistance especially interesting as a possible mechanism. Although available studies do not definitively support causal relationships, they suggest that psychosocial factors may be involved in the aetiology of inflammatory periodontal diseases, which, in turn, would relate to clinical management of these conditions.

Animals↗
PubMed1992

Evaluation of an automated system for hemoglobin measurement in animals.

In veterinary medicine, PCV determined by centrifugation of blood in a microhematocrit tube is the most common clinical test used to initially assess and monitor anemic and polycythemic animals. In contrast, blood hemoglobin (Hb) concentration, rather than PCV, is generally determined in human patients. One automated system photometrically measures blood Hb concentration after conversion of Hb to azide methemoglobin without dilution and was found to be a simple and accurate instrument for use in human medicine. We evaluated the system for its accuracy in measuring blood Hb concentration in animals by comparing it with standard techniques and for its suitability in veterinary practice. Blood samples, anticoagulated with potassium EDTA, from 78 healthy animals (33 dogs, 17 cats, 13 horses, and 15 cows) and 58 dogs and 4 cats with various blood abnormalities (10 anemia, 11 polycythemia, 21 lipemia, 16 leukocytosis, and 6 icterus) were analyzed. In all species, blood Hb concentration of healthy animals determined by the system was comparable to that measured by standard cyanmethemoglobin methods (ie, an automated counter; rI = 0.987 to 0.998 and a hemoglobin kit, rI = 0.946 to 0.993). The aforementioned system also yielded similar values to those obtained by use of standard methods in anemic, polycythemic, and icteric dogs and cats. Moreover, the system reads the absorbance at 2 wavelengths to correct for turbidity, and therefore, accurately measured Hb concentration in blood samples with severe lipemia (triglycerides concentration > 500 mg/dl) and marked leukocytosis (> 50,000 WBC/microliter), whereas other standard Hb techniques are known to give falsely high results.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The effect of unilateral anteromedial cortex lesions on prey-catching and spatio-motor behaviour in the rat.

The neglect which follows a unilateral lesion of anteromedial cortex in rat was examined using two tasks. In the first task animals had to press the left bar of a two-bar Skinner box for food reward. In the second task animals captured live locusts presented in either their right or left visual field. The results showed that in the Skinner box there was a transitory spatial neglect contralateral to the lesion, which disappeared after 2-3 days. In the prey-catching task animals failed to target or track locusts when they were in the field contralateral to the lesion throughout the 4-day testing period. Capture and consummatory responses were normal when the locust was presented (or moved independently) into the ipsilateral (non-neglected) field. 60 days later the asymmetrical response to locusts in the contralateral field had disappeared.

Animals↗
PubMed1990

Performance on two fixed-interval schedules in the absence of neocortex in rats.

Rats with complete surgical removal of the neocortex (neodecorticates) were trained, with milk as the reinforcer, on a 40-s fixed-interval (FI-40) schedule, then on an FI-120, and finally reexposed to the FI-40. Like controls, neodecorticates developed and appropriately adjusted their postreinforcement pauses and response distributions and showed scallop-type responding on the FI-120 and a positive correlation between running rate and the preceding postreinforcement pause on both FI-40 schedules but not on the FI-120. On some variables neodecorticates reached asymptotic levels of performance more slowly than controls. Extended training on the first FI-40 did not differentially affect neodecorticates' performance. The results suggest that neodecorticates retain a functional timing mechanism.

Animals↗
PubMed1989

Anomalous patterns of response learning and transfer in decorticate rats.

Behavioural flexibility in decorticate rats was examined by testing response transfer in an obstructed alleyway. In the first experiment, rats were trained to push a ball out of a cylindrical alleyway in order to gain access to the goal box. When this 'push' habit was prevented by blocking forward movement of the ball, decorticate rats were much quicker than sham-operated rats in successfully developing the novel clearance response of pulling the ball into the start box. Both groups were subsequently able to reverse effectively between responses. In a second experiment, sham-operated and decorticate rats were first shaped to pull the ball clear from the alleyway, and then required to adopt a push-type clearance response when movement of the ball towards the start box was prevented. Here, the decorticates showed difficulty both in learning to pull the ball out of the alley and in transferring to a push-type clearance response, but having transferred they coped well with subsequent reversals. This asymmetrical pattern of transfer results is not readily attributed to response preference and raises the possibility that, in some situations at least, decorticated animals may show greater behavioural flexibility than had previously been supposed.

Animals↗
PubMed1989

Autoshaping in micrencephalic rats.

An autoshaping procedure in which the illumination of a lever was predictive of food reinforcement was used to compare learning in rats with micrencephaly induced by irradiation on the 16th day of gestation and in sham-irradiated controls. Both groups showed equivalent levels of lever-directed activity, and the micrencephalic animals differentiated as well as the control animals between the predictive lever and a nonpredictive lever. The micrencephalic animals were able to redistribute their lever-directed activity when the significance of the levers was reversed and did so more readily than the control animals. Results support the claim that association learning survives either traumatic or developmental neocortical damage and have implications for remedial procedures following both head injury and developmental cerebral pathology in humans.

Animals↗