The influence of different error estimates in the detection of post-operative cognitive dysfunction using reliable change indices with correction for practice effects.

The reliable change index (RCI) expresses change relative to its associated error, and is useful in the identification of post-operative cognitive dysfunction (POCD). This paper examines four common RCIs that each account for error in different ways. Three rules incorporate a constant correction for practice effects and are contrasted with the standard RCI that had no correction for practice. These rules are applied to 160 patients undergoing coronary artery bypass graft (CABG) surgery who completed neuropsychological assessments preoperatively and 1 week post-operatively using error and reliability data from a comparable healthy non-surgical control group. The rules all identify POCD in a similar proportion of patients, but the use of the within subject standard deviation, expressing the effects of random error, as an error estimate is a theoretically appropriate denominator when a constant error correction, removing the effects of systematic error, is deducted from the numerator in a RCI.     

Health experiences and employment status in subjects with chronic back pain: a long-term perspective.

The purpose of this study was to describe health experiences, focused on gender and return to work, in subjects with chronic low back pain in a long-term perspective. The convenient sample consisted of 12 subjects who had attended a pain rehabilitation program 6 years earlier. Typed interviews were transcribed, and a content analysis approach was used. Five categories were found: coping, root causes, control/influence, pain, and sleep. The interviews showed that the subjects expressed well-being, although pain had become part of their daily life. However, both gender and well-being group differences were identified. The women and the group with reduced well-being used the root causes category in a higher degree than the men and the well-being group did. The conclusion is that there are differences according to both gender and return to work within the subjects with chronic pain and that these differences are related to both root causes and coping pattern.     

Dioxin concentrations in the blood of workers at municipal waste incinerators.

OBJECTIVES--Increased concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs) in pooled blood samples from workers at municipal waste incinerators have been reported. This study was undertaken to confirm these results in individual blood samples from potentially exposed and unexposed workers at municipal waste incinerators compared with matched unexposed controls and compared with concentrations in the slag and fly ash from the municipal waste incinerators. METHODS--Concentrations of PCDDs and PCDFs were determined in the blood of 10 workers from an old municipal waste incinerator without adequate pollution controls, 11 workers from a newer incinerator with modern pollution controls, and 25 controls from the general population group matched for age (+/- 10 years), sex, and race, and in the slag and fly ash from the older incinerator. RESULTS--Significant increases of certain PCDDs and PCDFs were found in the blood of the workers from the older incinerator compared with the controls as follows: octaCDD (1051 (438) v 637 (344), P < 0.001), hexaCDF (52.3 (28.7) v 30.2 (18.2), P < 0.01), heptaCDF (43.9 (30.4) v 22.7 (12.4), P < 0.001), total PCDDs (1262 (484) v 825 (454), P < 0.001), total PCDFs (133.0 (68.1) v 93.7 (36.7), P < 0.05), and total PCDD/Fs (1395 (537) v 918 (437), P < 0.001). The workers from the older incinerator with the greatest exposure were found to have the most significant increases of the blood PCDDs and PCDFs, and the pattern of increased PCDD and PCDF congeners in the blood corresponded to the pattern in the incinerator slag and ash. No significant differences were found between the blood concentrations of the workers at the newer incinerator and the controls. CONCLUSION--Occupational exposure to slag and fly ash from municipal waste incinerators may increase the blood concentrations of PCDDs and PCDFs. Modern pollution control technology in new incinerators may be able to minimise potential exposure to slag and fly ash and thus the absorption of PCDDs and PCDFs from this source.     

Cyclic AMP levels of C6 glioma cells treated with cis-dichlorodiammine platinum (cis-DDP)

Rat C6 glioma cells were cultured for 3-4 days in MEM supplemented with bovine serum. After 10 min incubation of cells with 0.075, 1.0 or 7.5 micrograms ml-1 cis-DDP the basal cAMP levels (7.87 +/- 0.4 pmoles mg-1 protein) were not affected. In the presence of a phosphodiesterase inhibitor, IBMX, an increase of cAMP occurred; the later was more pronounced in cis-DDP treated cells than in the controls. This suggests that both adenylate cyclase and cAMP-phosphodiesterase were proportionally influenced at this period and that the stimulatory effect of cis-DDP on AC could be demonstrated only when increased activity of PDE had been blocked by IBMX. At later time intervals (10 h-40 h), a 5- to 17-fold elevation of cAMP levels was observed even in the absence of IBMX. Pretreatment of the cells with cis-DDP significantly potentiated cAMP accumulation in response to NE alone and to cis-DDP plus NE could be prevented to a large extent by propranolol; in cis-DDP treated cells the propranolol protection was more effective, both in the absence and the presence of IBMX. The pretreatment of cells with an alpha-blocker, Regitin, did not significantly influence cAMP accumulation. The results indicate that the cis-DDP stimulated cAMP response to NE is mediated via an interaction with beta-adrenergic receptors. The late increase in cAMP content may be a mediator of the morphological changes in these cells following exposure to cis-DDP.     

Effects of postoperative pain on lung volume in patients undergoing aortic surgery

To evaluate the potential advantages of the administration of extradural morphine to control postoperative pain and its effects on respiratory function, 39 patients were randomly assigned to one of two groups before aortic surgery. The first group (20 patients) received intravenous analgesia as required (control group). The second group (19 patients) received extradural morphine in a programmed fashion. During the immediate postoperative period the following parameters were measured in both groups: respiratory rate, vital capacity, peak expiratory volume in the first second, PaO2, PaCO2, arterial pH, heart rate, and systolic and diastolic blood pressure. In the group treated with morphine the postoperative increase in heart and respiratory rate was significantly smaller than in the control group (p less than 0.01). Postoperative forced pulmonary volumes were higher in the morphine group (p less than 0.01). However, there were no differences in time of hospitalization between both groups. There were more complications in the control group, but the difference did not reach statistical significance.     

Contraction-specific differences in maximal muscle power during stretch-shortening cycle movements in elderly males and females

Elderly people (age 75 years; n=48 males and 34 females) were studied in order to elucidate gender differences in elderly subjects on the determinants of muscle power (force and velocity) during a stretch-shortening cycle. All subjects performed three maximal counter-movement vertical jumps using both legs, on a force platform (Kistler 9281 B). The eccentric (Ep) and concentric (Cp) phases of the jumps were analyzed. The Ep was further divided into an acceleration phase (Ep_acc: from the start of the downward movement to the maximal negative velocity) and deceleration phase (Ep_dec: from the maximal negative velocity to the end of the downward movement). Jump height for the men was higher than for the women (P < 0.001). During both Ep_acc and Ep_dec no significant differences were observed between males and females in force and power generation. However, the men had a higher peak muscle power during the Cp, which may be explained exclusively by the velocity determinant (P < 0.001). No specific gender-related strategy appeared to influence the motor pattern of the movement. The comparable eccentric force generation of the leg extensors in both genders suggests a similar ability to cope with eccentric muscle actions during everyday activities. In contrast, the marked lower capacity for concentric contractions in women may result in an impaired performance, especially in activities where intense and rapid movements are essential, for example when reversing a forward fall. This may be one reason why elderly women are more prone to falls than are elderly men. Accepted: 19 September 2000     

The Topography of Non-Linear Cortical Dynamics at Rest, in Mental Calculation and Moving Shape Perception

Differential cortical activation by cognitive processing was studied using dimensional complexity, a measure derived from nonlinear dynamics that indicates the degrees of freedom (complexity) of a dynamic system. We examined the EEG of 32 healthy subjects at rest, during a visually presented calculation task, and during a moving shape perception task. As a nonlinear measure of connectivity, the mutual dimension of selected electrode pairs was used. The first Lyapunov coefficient was also calculated. Data were tested for non-linearity using a surrogate data method and compared to spectral EEG measures (power, coherence). Surrogate data testing confirmed the presence of nonlinear structure in the data. Cognitive activation led to a highly significant rise in dimensional complexity. While both tasks activated central, parietal and temporal areas, mental arithmetic showed frontal activation and an activity maximum at T3, while the moving shape task led to occipital activation and a right parietal activity maximum. Analysis of mutual dimension showed activation of a bilateral temporal-right frontal network in calculation. The Lyapunov coefficent showed clear topographic variation, but was not significantly changed by mental tasks (p<.09). While dimensional complexity was almost unrelated to power values, nonlinear (mutual dimension) and linear (coherence) measures of connectivity shared up to 37% of variance. Data are interpreted in terms of increased cortical complexity as a result of recruitment of asynchronously active, distributed neuronal assemblies in cognition. The topography of nonlinear dynamics are related to neuropsychological and neuroimaging findings on mental calculation and moving shape perception.     

SSCP analysis of paraffin wax embedded tissues in a family with an atypical form of Fabry disease

To investigate the distribution of a single base pair mutation within a family with one known case of Fabry disease, DNA from paraffin wax embedded necropsy material was studied using single-strand conformation polymorphism (SSCP) analysis. The proband, who presented with an atypical form of Fabry disease, had a G to A transition in exon 6 of the α-galactosidase A gene. This patient had mainly cardiac symptoms and late onset disease. Further cases of coronary disorders occurred in this family, including the proband's brother who died at 42 years of age of a cardiac disorder. Formalin fixed, paraffin wax embedded material from the brother and two more distant relatives was available for analysis. SSCP analysis showed that the proband's brother also carried the G to A transition. Thus, the atypical form of Fabry disease and unrelated cardiac diseases with similar clinical symptoms occurred within a single family. The variant form is rare but may account for a few of the numerous cases of cardiac disease in men and should be considered when clusters of cases of cardiac disease occur within a single family.