Baseline Pupil Size Seems Unrelated to Fluid Intelligence, Working Memory Capacity, and Attentional Control

Over the past few years, several studies have explored the relationship between resting-state baseline pupil size and cognitive abilities, including fluid intelligence, working memory capacity, and attentional control. However, the results have been inconsistent. Here we present the findings from two experiments designed to replicate and expand previous research, with the aim of clarifying previous mixed findings. In both experiments, we measured baseline pupil size while participants were not engaged in any tasks, and assessed fluid intelligence using a matrix task. In one experiment we also measured working memory capacity (letter-number-sequencing task) and attentional control (attentional-capture task). We controlled for several personal and demographic variables known to influence pupil size, such as age and nicotine consumption. Our analyses revealed no relationship between resting-state pupil size (average or variability) and any of the measured constructs, neither before nor after controlling for confounding variables. Taken together, our results suggest that any relationship between resting-state pupil size and cognitive abilities is likely to be weak or non-existent.

Subjective Socioeconomic Status, Cognitive Abilities, and Personal Control: Associations With Health Behaviours

Objective

To examine subjective and objective socioeconomic status (SSES and OSES, respectively) as predictors, cognitive abilities as confounders, and personal control perceptions as mediators of health behaviours.

Design

A cross-sectional study including 197 participants aged 30–50 years, recruited from the crowd-working platform, Prolific.

Main Outcome Measure

The Good Health Practices Scale, a 16-item inventory of health behaviours.

Results

SSES was the most important predictor of health behaviours (beta = 0.19, p < 0.01). Among the OSES indicators, education (beta = 0.16, p < 0.05), but not income, predicted health behaviours. Intelligence (r = −0.16, p < 0.05) and memory (r = −0.22, p < 0.01) were negatively correlated with health-promoting behaviours, and the effect of memory was upheld in the multivariate model (beta = −0.17, p < 0.05). Personal control perceptions (mastery and constraints) did not act as mediators.

Conclusion

SSES predicted health behaviours beyond OSES. The effect of socioeconomic indicators was not confounded by cognitive abilities. Surprisingly, cognitive abilities were negatively associated with health-promoting behaviours. Future research should emphasise SSES as a predictor of health behaviours. Delineating the psychological mechanisms linking SSES with health behaviours would be a valuable contribution toward improved understanding of socioeconomic disparities in health behaviours.

Mental Effort When Playing, Listening, and Imagining Music in One Pianist's Eyes and Brain

We investigated "musical effort" with an internationally renowned, classical, pianist while playing, listening, and imagining music. We used pupillometry as an objective measure of mental effort and fMRI as an exploratory method of effort with the same musical pieces. We also compared a group of non-professional pianists and non-musicians by the use of pupillometry and a small group of non-musicians with fMRI. This combined approach of psychophysiology and neuroimaging revealed the cognitive work during different musical activities. We found that pupil diameters were largest when "playing" (regardless of whether there was sound produced or not) compared to conditions with no movement (i.e., "listening" and "imagery"). We found positive correlations between pupil diameters of the professional pianist during different conditions with the same piano piece (i.e., normal playing, silenced playing, listen, imagining), which might indicate similar degrees of load on cognitive resources as well as an intimate link between the motor imagery of sound-producing body motions and gestures. We also confirmed that musical imagery had a strong commonality with music listening in both pianists and musically naïve individuals. Neuroimaging provided evidence for a relationship between noradrenergic (NE) activity and mental workload or attentional intensity within the domain of music cognition. We found effort related activity in the superior part of the locus coeruleus (LC) and, similarly to the pupil, the listening and imagery engaged less the LC-NE network than the motor condition. The pianists attended more intensively to the most difficult piece than the non-musicians since they showed larger pupils for the most difficult piece. Non-musicians were the most engaged by the music listening task, suggesting that the amount of attention allocated for the same task may follow a hierarchy of expertise demanding less attentional effort in expert or performers than in novices. In the professional pianist, we found only weak evidence for a commonality between subjective effort (as rated measure-by-measure) and the objective effort gauged with pupil diameter during listening. We suggest that psychophysiological methods like pupillometry can index mental effort in a manner that is not available to subjective awareness or introspection.

The effects of cognitive abilities and task demands on tonic and phasic pupil sizes

Previous studies on individual differences in pupil size of healthy individuals and their relation to performance have been inconclusive. Using a novel approach, we tested the effect of general cognitive abilities and level of task performance on pretrial baseline and task-evoked pupil (TEP) sizes (N = 116) while we manipulated the level of task demands using a multiple object tracking task. Results did not reveal an effect of general cognitive abilities, estimated by working memory capacity and gF scores, on either baseline or TEP sizes. In contrast, we found an interaction in TEP sizes between level of overall MOT performance and task demands. We propose that individual differences in TEP sizes are related to state-specific level of task performance and task demands, probably in combination with other factors like age, personality traits, and state-specific level of motivation and arousal. We also suggest methodological confounds that may cause the previous inconclusive findings.

Pupillary and behavioral markers of alerting and orienting: An individual difference approach

Measuring task-evoked pupillary (TEP) responses as an index of phasic activity in the locus coeruleus (LC), we examined two competing hypotheses regarding the alerting and orienting mechanisms of attention. According to a dual mechanism account (Fernandez-Duque & Posner, 1997), two separate noradrenergic and cholinergic mechanisms modulate, respectively, the alerting and orienting effects. However, Corbetta and colleagues (2008) proposed that LC phasic activity may also be involved in orienting effect through its functional relationship with the ventral attentional network. We recruited seventy-five healthy Norwegian participants to perform a Posner cueing task. Both behavioral and pupillary responses revealed the alerting effect. Also, both behavioral and pupillary responses indicated that cued attention is affected by age. Behavioral responses also revealed orienting effect However, we found no TEP differences between valid, invalid, and neutral conditions, suggesting that TEP effects were driven by the alerting effect of cue presentation. Moreover, both behavioral and pupillary estimates of alertness and orienting were uncorrelated. Finally, individual differences in general cognitive abilities did not appear to affect the orienting and alerting mechanisms. This pattern of results is consistent with the dual mechanism account of attention. However, the LC involvement in the (re)orienting attention may be driven by state-specific factors.

Distinct Neural Mechanisms Meet Challenges in Dynamic Visual Attention due to Either Load or Object Spacing

When engaged in dynamic visuospatial tasks, the brain copes with perceptual and cognitive processing challenges. During multiple-object tracking (MOT), the number of objects to be tracked (i.e., load) imposes attentional demands, but so does spatial interference from irrelevant objects (i.e., close encounters). Presently, it is not clear whether the effect of load on accuracy solely depends on the number of close encounters. If so, the same cognitive and physiological mechanisms deal with increasing load by preparing for and dealing with spatial interference. However, this has never been directly tested. Such knowledge is important to understand the neurophysiology of dynamic visual attention and resolve conflicting views within visual cognition concerning sources of capacity limitations. We varied the processing challenge in MOT task in two ways: the number of targets and the minimum spatial proximity between targets and distractors. In a first experiment, we measured task-induced pupil dilations and saccades during MOT. In a separate cohort, we measured fMRI activity. In both cohorts, increased load and close encounters (i.e., close spatial proximity) led to reduced accuracy in an additive manner. Load was associated with pupil dilations, whereas close encounters were not. Activity in dorsal attentional areas and frequency of saccades were proportionally larger both with higher levels of load and close encounters. Close encounters recruited additionally ventral attentional areas that may reflect orienting mechanisms. The activity in two brainstem nuclei, ventral tegmental area/substantia nigra and locus coeruleus, showed clearly dissociated patterns. Our results constitute convergent evidence indicating that different mechanisms underlie processing challenges due to load and object spacing.

Proactive and reactive modes of cognitive control can operate independently and simultaneously

Cognitive control enables optimal biasing of attention, perception, and actions in the service of mental or behavioral goals. To understand the variability of applied cognitive control, we need to unravel the relation between two underlying mechanisms: proactive and reactive modes. During proactive cognitive control, goal-relevant information is selected before the occurrence of a cognitively demanding event, and is actively maintained for as long as required by the task. During reactive mode, cognitive control is transiently activated only after the cognitively demanding event has occurred. Mechanistically, proactive and reactive control modes may be at least semi-independent and engaged simultaneously, but this has so far not been demonstrated empirically. Situational demands and an individual's cognitive capacity and motivation may bias behavior towards one or the other mode. Reward induces more proactive processing in the AX-CPT task, whereas context load induces reactive processing. We combined these manipulations to investigate the extent to which proactive and reactive control modes can operate independently and simultaneously. The results replicated already published effects of reward incentives and context load. Most importantly, these effects were essentially independent of each other, suggesting that proactive and reactive cognitive control modes depend on separate information-processing and neural mechanisms. The results also show that while proactive processing is influenced by reward, reactive processing seems independent of such factor. These findings have implications for our understanding of the structure of cognitive control and cognitive motivation, and are relevant for the design of interventions to improve cognitive control in various developmental and neuropsychiatric groups.

Autoimmune encephalitis associated with antibodies against the metabotropic glutamate receptor type 1: case report and review of the literature

Autoimmune encephalitis associated with antibodies against the metabotropic glutamate receptor type 1 is a rare autoimmune disease with only 18 cases being described in the literature so far. Most patients present with subacute cerebellar ataxia. In more than one third of cases a paraneoplastic aetiology has been suspected. Here we report a case of a 45-year-old man without known malignancy, who presented with progressive dysarthria and subsequently developed subacute cerebellar ataxia. Immunotherapy with glucocorticoids, i.v. immunoglobulins and rituximab improved clinical symptoms and resulted in a stable disease course up to the present. The article describes the clinical course of the patient with a follow-up-period of approximately 24 months and reviews the cases reported in the literature so far.

Individual differences in resting-state pupil size: Evidence for association between working memory capacity and pupil size variability

Dynamic non-luminance-mediated changes in pupil diameter have frequently been shown to be a reliable index for the level of arousal, mental effort, and activity in the locus coeruleus, the brainstem's noradrenergic arousal center. While pupillometry has most commonly been used to assess the level of arousal in particular psychological states or the level of engagement in cognitive tasks, some recent studies have found a relationship between average resting-state (i.e. baseline) pupil sizes and individuals' working memory capacity (WMC), indicating that individuals with higher WMC on average have larger pupils than individuals with relatively lower WMC. In the present study, we measured pupil size continuously in 212 participants during rest (i.e. while fixating) and estimated WMC in all participants by administering the Letter-Number Sequencing (LNS) task from WAIS-III. We were unable to replicate the relation between average pupil size and WMC. However, the novel finding was that higher WMC was associated with higher variability in resting-state pupil size. The present results are relevant for the current debate on the role of noradrenergic activity on working memory capacity.

Chasing Animals With Split Attention: Are Animals Prioritized in Visual Tracking?

Some evolutionary psychologists have hypothesized that animals have priority in human attention. That is, they should be detected and selected more efficiently than other types of objects, especially man-made ones. Such a priority mechanism should automatically deploy more attentional resources and dynamic monitoring toward animal stimuli than nonanimals. Consequently, we postulated that variations of the multiple object or identity tracking and multiple event monitoring tasks should be particularly suitable paradigms for addressing the animate monitoring hypothesis, given their dynamic properties and dependency on divided attention. We used images of animals and artifacts and found neither a substantial sign of improvement in tracking the positions associated with animal stimuli nor a significant distracting effect of animals. We also failed to observe a significant prioritization in orders of response for positions associated with animals. While we observed an advantage for animals in event monitoring, this appeared to be dependent on properties of the task, as confirmed in further experiments. Moreover, we observed a small but inconclusive advantage for animals in identity accuracy. Thus, under certain conditions, some bias toward animals could be observed, but the evidence was weak and inconclusive. To conclude, effect sizes were generally small and not conclusively in favor of the expected attentional bias for animals. We found moderate to strong evidence that images of animals do not improve positional tracking, do not act as more effective distractors, are not selected prior to artifacts in the response phase, and are not easier to monitor for changes in size.

The "face race lightness illusion": An effect of the eyes and pupils?

In an internet-based, forced-choice, test of the ‘face race lightness illusion’, the majority of respondents, regardless of their ethnicity, reported perceiving the African face as darker in skin tone than the European face, despite the mean luminance, contrast and numbers of pixels of the images were identical. In the laboratory, using eye tracking, it was found that eye fixations were distributed differently on the African face and European face, so that gaze dwelled relatively longer onto the locally brighter regions of the African face and, in turn, mean pupil diameters were smaller than for the European face. There was no relationship between pupils’ size and implicit social attitude (IAT) scores. In another experiment, the faces were presented either tachistoscopically (140 ms) or longer (2500 ms) so that, when gaze was prevented from looking directly at the faces in the former condition, the tendency to report the African face as “dark” disappeared, but it was present when gaze was free to move for just a few seconds. We conclude that the presence of the illusion depends on oculomotor behavior and we also propose a novel account based on a predictive strategy of sensory acquisition. Specifically, by differentially directing gaze towards to facial regions that are locally different in luminance, the resulting changes in retinal illuminance yield respectively darker or brighter percepts while attending to each face, hence minimizing the mismatch between visual input and the learned perceptual prototypes of ethnic categories.

Isocyanurate formation during rigid polyurethane foam assembly: a mechanistic study based on in situ IR and NMR spectroscopy

Unravelling the role and working principle of the catalyst.

Animals Do Not Induce or Reduce Attentional Blinking, But They Are Reported More Accurately in a Rapid Serial Visual Presentation Task

Evolutionary psychologists have suggested that modern humans have evolved to automatically direct their attention toward animal stimuli. Although this suggestion has found support in several attentional paradigms, it is not without controversy. Recently, a study employing methods customary to studying the attentional blink has shown inconclusive support for the prioritization of animals in attention. This showed an advantage for reporting animals as second targets within the typical window of the attentional blink, but it remained unclear whether this advantage was really due to a reduction of the attentional blink. We reassessed for the presence of a reduced attentional blink for animals compared with artifacts by using three disparate stimuli sets. A general advantage for animals was found but no indication of a reduction of the attentional blink for animals. There was no support for the prediction that animal distractors should lead to spontaneous inductions of attentional blinks when presented as critical distractors before single targets. Another experiment with single targets still showed that animals were reported more accurately than artifacts. A final experiment showed that when animals were first target, they did not generate stronger attentional blinks. In summary, we did find a general advantage for animal images in the rapid serial visual presentation task, but animal images did not either induce or reduce attentional blinks. This set of results is in line with conclusions from previous research showing no evidence for a special role of animals in attention.

Major involvement of trunk muscles in myotonic dystrophy type 1

OBJECTIVES

The motor impairments in Myotonic Dystrophy 1 (DM1) are assumed to progress from distal toward proximal parts of the extremities in the Juvenile and Adult forms of DM1. On occasion and late in progress spine deformity is observed. In this study we have examined whether and to what extent trunk muscles are impaired in DM1, and if this impairment is correlated with the duration of the disorder, walking capacity, mobility, balance, and CTG-repeats.

MATERIALS & METHODS

Manual muscle testing (MMT) of skeletal muscle strength in trunk and extremities, reassessment of the mutation size, time since first symptom, the 6 min walk test (6MWT), Rivermead mobility index (RIM) and Timed up & go (TUG) were sampled in 38 adult DM1 outpatients.

RESULTS

We found significant impairment in trunk muscles. Trunk muscle strength decreased significantly with increasing mutation size (r = -0.64, P < 0.001). Reduced walking capacity, mobility and balance were significantly related to decreased trunk muscle strength.

CONCLUSION

DM1 affects trunk muscle groups. The trunk impairments seem to occur relatively early in disease progression. Awareness of trunk impairments may be of importance for everyday functioning and for understanding the risk of injuries due to falls reported among DM1 patients. It may also help in identification of DM1 patients and considered outcome measure in future clinical trials.

The Change Detection Advantage for Animals: An Effect of Ancestral Priorities or Progeny of Experimental Design?

The "animate monitoring" hypothesis proposes that humans are evolutionarily predisposed to recruit attention toward animals. Support for this has repeatedly been obtained through the change detection paradigm where animals are detected faster than artifacts. The present study shows that the advantage for animals does not stand up to more rigorous experimental controls. Experiment 1 used artificially generated change detection scenes and counterbalanced identical target objects across two sets of scenes. Results showed that detection performance is determined more by the surrounding scene than semantic category. Experiment 2 used photographs from the original studies and replaced the target animals with artifacts in the exact same locations, such that the surrounding scene was kept constant while manipulating the target category. Results replicated the original studies when photos were not manipulated but agreed with the findings of our first experiment in that the advantage shifted to the artifacts when object categories replaced each other in the original scenes. A third experiment used inverted and blurred images so as to disrupt high-level perception but failed to erase the advantage for animals. Hence, the present set of results questions whether the supposed attentional advantage for animals can be supported by evidence from the change detection paradigm.

Differences in anatomy and kinematics in Asian and Caucasian TKA patients: influence on implant positioning and subsequent loading conditions in mobile bearing knees

The objective of our study was to determine the mechanical stress conditions under tibiofemoral loading with an overlay of knee kinematics in deep flexion on two different mobile bearing designs in comparison to in vivo failure modes. This study investigates the seldom but severe complication of fatigue failure of polyethylene components at mobile bearing total knee arthroplasty designs. Assuming a combination of a floor-based lifestyle and tibial malrotation as a possible reason for a higher failure rate in Asian countries we developed a simplified finite element model considering a tibiofemoral roll-back angle of 22° and the range of rotational motion of a clinically established floating platform design (e.motion FP) at a knee flexion angle of 120° in order to compare our results to failure modes found in retrieved implants. Compared to the failure mode observed in the clinical retrievals the locations of the occurring stress maxima as well as the tensile stress distribution show analogies. From our observations, we conclude that the newly introduced finite element model with an overlay of deep knee flexion (lateral roll-back) and considerable internally rotated tibia implant positioning is an appropriate analysis for knee design optimizations and a suitable method to predict clinical failure modes.

Utilizing hydrogen sulfide as a novel anti-cancer agent by targeting cancer glycolysis and pH imbalance

BACKGROUND AND PURPOSE

Many disparate studies have reported the ambiguous role of hydrogen sulfide (H2 S) in cell survival. The present study investigated the effect of H2 S on the viability of cancer and non-cancer cells.

EXPERIMENTAL APPROACH

Cancer and non-cancer cells were exposed to H2 S [using sodium hydrosulfide (NaHS) and GYY4137] and cell viability was examined by crystal violet assay. We then examined cancer cellular glycolysis by in vitro enzymatic assays and pH regulator activity. Lastly, intracellular pH (pHi ) was determined by ratiometric pHi measurement using BCECF staining.

KEY RESULTS

Continuous, but not a single, exposure to H2 S decreased cell survival more effectively in cancer cells, as compared to non-cancer cells. Slow H2 S-releasing donor, GYY4137, significantly increased glycolysis, leading to overproduction of lactate. H2 S also decreased anion exchanger and sodium/proton exchanger activity. The combination of increased metabolic acid production and defective pH regulation resulted in an uncontrolled intracellular acidification, leading to cancer cell death. In contrast, no significant intracellular acidification or cell death was observed in non-cancer cells.

CONCLUSIONS AND IMPLICATIONS

Low and continuous exposure to H2 S targets metabolic processes and pH homeostasis in cancer cells, potentially serving as a novel and selective anti-cancer strategy.

Oxa-azonia-boratacyclopentanes by Insertion of Dimethylaminobis(trifluoromethyl)borane into Epoxides

Dimethylaminobis(trifluoromethyl)borane, (CF3)2BNMe2 (A), reacts with epoxides of the general formula to yield five-membered heterocycles

(CF3)2 , R = Me (1), CH,F (2), CF3 (3), Et (4), Bz (5). With R = Ph a 1:2 mixture of the isomers (CF3)2 O (6a) and (CF3)2 (6b) is obtained. To the contrary, and A form the borane-dimethylamine adduct (H2C=CMe—CH2-O)(CF3)2B • NHMe2 (7). The compounds have been characterized by elemental analyses, multinuclear NMR, IR and mass spectra.

Assessing the performance of a bdelloid rotifer Philodina acuticornis odiosa acute toxicity assay

A bioassay using the bdelloid rotifer, Philodina acuticornis odiosa, was evaluated for use as a standard test method for direct toxicity assessment testing in the Australasian region. Philodina acuticornis odiosa was found to be relatively tolerant to phenol (24 h LC50, 142 mg/L). The mortality endpoint was both reliable and repeatable (the coefficients of variation for mortality at the 24 h LC50 concentration ranged from 11%-24% (n = 8)), sufficiently low to warrant further testing with a range of reference toxicants, so that this organism can be included for use as a regulatory test in Australasia.

[Developmental venous anomaly (DVA)]

As congenital anatomic variants of venous drainage, developmental venous anomalies (DVA) represent up to 60% of all cerebral vascular malformations. The prior term "venous angioma" is a misnomer implicating an abnormal vascular structure with an increased bleeding risk. They are often found incidentally and are hardly ever symptomatic. Their morphologic characteristics are dilated vessels in the white matter, which converge on a greater collector vein, forming the typical caput medusae. They drain into the superficial or deep venous system. The frequent association with other, potentially bleeding-prone vascular malformations is clinically relevant, in particular cavernous angioma, which might require therapeutic action. Therefore, coincident vascular lesions need to be actively sought by appropriate additional imaging techniques.

[Cavernous malformations]

Cavernomas of the CNS may involve brain parenchyma as well as the spinal cord and belong to those cerebrovascular malformations that have no arteriovenous shunt and thus are generally angiographically occult. Contrary to computed tomography (CT), which is generally suited to reveal calcifications or acute bleeding, magnetic resonance imaging (MRI) enables detection of even small cavernomas. A frequently associated venous anomaly is helpful for correct diagnosis.

Hippocampal volume reduction and HPA-system activity in major depression

Structural imaging studies investigating hippocampal volumes in patients suffering from major depression have yielded mixed results. Here, 24 unipolar depressed in-patients and 14 healthy controls carefully matched for age, gender, and years of education underwent quantitative magnetic resonance imaging (MRI). Saliva cortisol was measured at 0800 and 1600 h in patients during a one-week wash-out and the following 4 weeks. Hippocampal volumes were significantly reduced in the patient group even after adjusting for intracranial brain volume (ICV) and age. Across groups, age was significantly negatively correlated with uncorrected hippocampal volumes. In patients, severity of disease (baseline HAMD scores) and baseline cortisol levels were not related to hippocampal volumes. However, there was a negative association between duration of the index episode before hospitalization and hippocampal volumes. Additionally, hippocampal volumes were significantly negatively correlated with duration of illness. Finally, we observed a trend for higher hippocampal volumes in those patients who showed a subsequent decrease in cortisol levels under pharmacotherapy.

Apparent diffusion coefficient in vasogenic edema and reactive astrogliosis

INTRODUCTION

Distinguishing between vasogenic edema and reactive astrogliosis may be difficult in some instances. This study was performed to test the hypothesis that diffusion-weighted (DW) imaging with apparent diffusion coefficient (ADC) maps can be used to differentiate these two types of changes.

METHODS

The study population included 11 patients with perilesional vasogenic edema and 11 patients with gliosis examined with conventional MR imaging and DW imaging. The signal intensities of conventional pulse sequences and ADC values were calculated in regions of interest placed in the hyperintense edematous or gliotic regions and compared with those of normal-appearing white matter. Signal intensity ratios and ADC values in gliosis were compared with those in vasogenic edema using the Mann-Whitney U-test.

RESULTS

While considerable overlap was present for signal intensity ratios on conventional MR images, areas of gliosis demonstrated significantly higher ADC values (1.76 +/- 0.09 x 10(-3) mm(2)/s) than areas of vasogenic edema (1.35 +/- 0.06 x 10(-3) mm(2)/s; P < 0.0001) without overlap.

CONCLUSION

ADC values are helpful in differentiating reactive gliosis from vasogenic edema.

[Intracranial tumors in pediatric patients]

Every year, 400 children suffer from a brain tumor. These are the most frequent solid tumors in the pediatric patient. They represent a very heterogenic group of tumors with different clinical symptoms, pathology, therapy and prognosis. Imaging modalities such as CT and MRI are important for the diagnosis and follow-up after therapy. Brain tumors in children are responsible for 15-20% of all brain tumors. Tumors of the central nervous system are the second most common tumors after leukemia. Infra- and supratentorial tumors occur in equal number, however, there are differences in the age of occurrence: supratentorial tumors occur more often within the first 2-3 years of life, whereas infratentorial tumors reach there peak between 4 and 10 years. After the tenth year, infra- and supratentorial tumors occur with equal frequency.

Diffusion-weighted MR imaging improves diagnosis of CNS lymphomas

The frequency of CNS lymphomas is increasing in immunocompetent as well as in immunocompromised patients and its incidence accounts for approximately 1-2% of all primary cerebral neoplasms. It is a challenge to recognize CNS lymphomas by MR imaging as early as possible in order to dispose an optimal therapy. The aim of this report is to demonstrate, how diffusion-weighted MR imaging improves the accuracy of the differential diagnosis of CNS lymphomas.

Personbezogene Kontextfaktoren, Teil I

The International Classification of Functioning, Disability and Health (ICF) does not yet classify personal contextual factors. To determine the interaction of these factors on activities and participation of a person as well as their influence on the probable outcome of interventions, they must be taken into account in individual sociomedical expertises. Therefore, a group of medical experts working for the social health insurance medical advisory boards in Germany compiled a proposal for a systematic classification of personal contextual factors into domains, categories and items with respect to the ethical guidelines of the ICF. In a second step the main issues were transferred into the preliminary draft for a short version which will be published later to give support for practical daily use in health insurance matters.

Screening for diabetes using HbA1c in elderly subjects

The objective of the study was to determine the prevalence of known diabetes among elderly subjects receiving nursing care in a north Norwegian population, to screen for new cases using HbA1c measurement and to evaluate the quality of care for those with diabetes. Men and women, with and without known diabetes, above 69 years and receiving nursing care either in an institution or in their own home in the municipality of Tromsø, were included. A health questionnaire was administered and HbA1c measured. An oral glucose tolerance test (OGTT) was performed in those with HbA1c > 6.5% (upper reference limit). A total of 788 subjects were evaluated for participation and 228 completed the study. Forty-six subjects (20.2%) had a previous diagnosis of diabetes. Their age was 80.1+/-5.9 years (mean+/-SD) and HbA1c level 7.6+/-1.4%. Most patients had their blood glucose measured weekly and 65% used blood pressure medication; on average they were seen by their private doctor four times a year and annually by an ophthalmologist. Six subjects with undiagnosed diabetes had HbA1c > 6.5%. Diabetes was confirmed in one, excluded in two and further testing declined in three. None of these six subjects had HbA1c > 7.0%. In conclusion, there is a high prevalence of diabetes among elderly subjects needing nursing care. The prevalence of undiagnosed diabetes in need of treatment, as evaluated by the HbA1c level, was low, indicating that the focus on diabetes and quality of care for the elderly in our area is fairly good.

ADC mapping of normal human brain

BACKGROUND

The quantification of diffusion conditions in normal human brain has been gaining more and more attention since diffusion weighted imaging (DWI) was proved to be an important tool in the evaluation of cerebral pathologies, especially regarding the diagnosis of hyperacute stroke. The purpose of this study was to investigate the apparent diffusion coefficient (ADC) and anisotropy index (AI) in normal human brain to evaluate physiological ADC values for an ADC mapping of different brain regions.

MATERIAL/METHODS

22 regions of interest (ROIs) in the ADC maps of 53 volunteers showing no cerebral pathologies were measured in the gray and white matter of the frontal, parietal and occipital lobes, the corpus callosum, and the lateral ventricles.

RESULTS

Apparent diffusion is quite inhomogeneous for different brain regions. In both subcortical white matter (ADC: 525 x 10(-8) mm2/s, AI: 0.05) and in gray matter (ADC: 1486 x 10(-8) mm2/s, AI: 0.05) diffusion was isotropic, while in periventricular white matter (ADC: 408 x 10(-8) mm2/s, AI: 0.34) and the corpus callosum (ADC: 799 x 10(-8) mm2/s, AI: 0.77) anisotropic.

CONCLUSIONS

With the exception of children and young adults, ADC seems to be intra- and interindividually constant, with no sex or age dependency for the patient sample we investigated (mean age: 62+/-9.4 years). Hence the measurement of ADC may provide an index of lesion severity.

Trägerübergreifende Aspekte der Begutachtung nach dem SGB IX

A project group of the Medical Advisory Board of the German Federal Rehabilitation Council (BAR) developed fundamental joint principles on experts' opinions according to the social law code no. IX (SGB IX). The principles aim at medical experts working in different social organisations and statutory health care insurance. It was intended to create a "sociomedical language" which should be used as jointly as possible by experts in rehabilitation and social medicine and which is based on the ICF (International Classification of Functioning, Disability and Health, WHO 2001). Its stringent application will increase the utility of medical expertise across different institutions. The authors recommend to evaluate whether this model could provide a tool in the communication and cooperation between different sectors of the health system. Part I describes the theoretical model, Part II its application to a virtual individual case history.

[Aspects of expertising which are jointly valid for German sociomedicine and statutory health care]

A project group of the Medical Advisory Board of the German Federal Rehabilitation Council (BAR) developed fundamental joint principles on experts' opinions according to the social law code no. IX (SGB IX). The principles aim at medical experts working in different social organisations and statutory health care insurances. It was intended to create a "sociomedical language" which should be used as jointly as possible by experts in rehabilitation and social medicine and which is based on the ICF (International Classification of Functioning, Disability and Health, WHO 2001). Its stringent application will increase the utility of medical expertise across different institutions. The authors recommend to evaluate whether this model could provide a tool in the communication and cooperation between different sectors of the health system. Part I describes the theoretical model, Part II its application to a virtual individual case history.

Three-dimensional true FISP for high-resolution imaging of the whole brain

While high-resolution T1-weighted sequences, such as three-dimensional magnetization-prepared rapid gradient-echo imaging, are widely available, there is a lack of an equivalent fast high-resolution sequence providing T2 contrast. Using fast high-performance gradient systems we show the feasibility of three-dimensional true fast imaging with steady-state precession (FISP) to fill this gap. We applied a three-dimensional true-FISP protocol with voxel sizes down to 0.5 x 0.5 x 0.5 mm and acquisition times of approximately 8 min on a 1.5-T Sonata (Siemens, Erlangen, Germany) magnetic resonance scanner. The sequence was included into routine brain imaging protocols for patients with cerebrospinal-fluid-related intracranial pathology. Images from 20 patients and 20 healthy volunteers were evaluated by two neuroradiologists with respect to diagnostic image quality and artifacts. All true-FISP scans showed excellent imaging quality free of artifacts in patients and volunteers. They were valuable for the assessment of anatomical and pathologic aspects of the included patients. High-resolution true-FISP imaging is a valuable adjunct for the exploration and neuronavigation of intracranial pathologies especially if cerebrospinal fluid is involved.

Time course of the apparent diffusion coefficient after cerebral infarction

The purpose of this study was to evaluate quantitative apparent diffusion changes in the center of infarction by measurement of the apparent diffusion coefficient (ADC), and to investigate the influence of ischemia on the contralateral hemisphere. By diffusion echo-planar imaging (EPI) 52 patients showing cerebral infarction were studied within 5 h to >12 months after onset of clinical symptoms. Using three diffusion gradient strengths (b1=30 s/mm(2); b2=300 s/mm(2), b3=1100 s/mm(2)) ADC maps were generated. After onset of ischemia, ADC in the center of infarction was lower than in the contralateral regions of human brain. At first ADC declined for approximately 28 h to a minimum of approximately 150x10(-8) cm(2)/s. Then the ADC reincreased and reached a "pseudonormalization" after approximately 5 days. Chronic infarctions did show much higher ADC values (2000x10(-8) cm(2)/s) than unaffected areas. Neither localization nor size of infarctions showed a significant influence on this time course. In the center of infarction diffusion is isotropic. Even brain regions of the contralateral hemisphere are influenced by cerebral ischemia. In these regions ADC is higher than for physiological conditions. The ADC also declines especially for the first 2-3 days after onset of symptoms, also followed by reincrease. The ADC calculation enables determination of the onset of infarction more exactly than is possible using only diffusion-weighted imaging. Diffusion in the center of infarction is isotropic; hence, orientation of the diffusion gradients has no significant influence on sensitivity of measurements. The calculation of the ADC ratio based on data derived from the center of infarction and the contralateral hemisphere seems to be critical because the ADC in the unaffected contralateral hemisphere also changes.

Pathophysiological changes after traumatic brain injury: comparison of two experimental animal models by means of MRI

In an experimental study MRI was used to compare the pathophysiological changes of brain tissue after lateral fluid percussion injury (FPI) versus cold injury (CI) as models of traumatic brain injury (TBI). Two groups of Sprague-Dawley rats (n=23) were subjected to mild FPI, respectively, CI localized over the right parietal cortex. MRI was performed at different time points including T1w, T2w and T1w-CE (Gd-DTPA 0.2 mmol/kg BW) sequences as well as perfusion-weighted imaging with calculation of regional cerebral blood volume (rCBV) and regional cerebral blood flow (rCBF). T2w and T1w-CE images showed hyperintense areas in the traumatised cortex demonstrating brain edema and blood-brain barrier (BBB)-breakdown increasing up to 12 h. Perfusion-weighted imaging demonstrated a significant decrease of rCBV and rCBF in the ipsilateral cortex of CI animals compared with the contralateral hemisphere. In contrast, rats of the FPI group showed only slight differences in rCBF and rCBV comparing the left and right cortex. The results of our study confirm that both mild FPI and CI produced focal brain edema with concomitant breakdown of the BBB as a model of TBI. Since differences regarding perfusion are much more pronounced in CI our results suggest that, this model more likely seems to reflect pathophysiological changes of brain ischemia, whereas FPI seems to be better suited to model the pathophysiological characteristics of TBI.

Mitochondrial uncoupling proteins in human physiology and disease

Uncoupling proteins are mitochondrial carrier proteins that catalyse a regulated proton leak across the inner mitochondrial membrane, diverting free energy from ATP synthesis by the mitochondrial F0F1-ATP synthase to the production of heat. Uncoupling protein 1 (UCP1), which is exclusively expressed in brown adipose tissue, is the mediator of thermogenesis in response to beta-adrenergic stimulation. Using gene a knockout mouse model, UCP1 has been shown to be required for cold acclimation. Two homologues of UCP1, UCP2 and UCP3, have been identified recently and show a much wider tissue distribution. UCP2 and UCP3 have been postulated to play a role in the regulation of cold acclimation, energy expenditure and diet-induced thermogenesis in humans, who, in contrast to rodents, have very little brown fat in adult life. However, evidence is accumulating that thermogenesis and regulation of body weight may not be the physiological functions of UCP2 and UCP3. For instance, mice deficient for UCP2 or UCP3 are not cold-intolerant and do not develop obesity. Alternative functions were suggested, primarily based on findings in UCP2 and UCP3 gene knockout mice. Both UCP2- and UCP3-deficient mice were found to overproduce reactive oxygen species and UCP2-deficient mice to hypersecrete insulin. Thus, the UCP1 homologues may play a role in regulating mitochondrial production of reactive oxygen species and b-cell function. In this review, we discuss the role of UCP1, UCP2 and UCP3 in human physiology and disease, primarily based on findings from the various animal models that have been generated.

Immunodetection of 3-nitrotyrosine in the liver of zymosan-treated rats with a new monoclonal antibody: comparison to analysis by HPLC

Zymosan-induced peritonitis is associated with an increased production of reactive nitrogen oxides that may contribute to the often-observed failure of multiple organ systems in this model of acute inflammation. Quantitative biochemical evidence is provided for a marked 13-fold increase in protein-bound 3-nitrotyrosine (NTyr), a biomarker of reactive nitrogen oxides, in liver tissue of zymosan-treated rats. In order to investigate the localization of NTyr in this affected tissue, a monoclonal antibody, designated 39B6, was raised against 3-(4-hydroxy-3-nitrophenylacetamido) propionic acid-bovine serum albumin conjugate and its performance characterized. 39B6 was judged by competition ELISA to be approximately 2 orders of magnitude more sensitive than a commercial anti-NTyr monoclonal antibody. Binding characteristics of 39B6 were similar, but not identical, to that of a commercial affinity-purified polyclonal antibody in ELISA and immunohistochemical analyses. Western blot experiments revealed high specificity of 39B6 against NTyr and increased immunoreactivity of specific proteins from liver tissue homogenates of zymosan-treated rats. Immunohistochemical analysis of liver sections indicated a marked zymosan-induced increase in immunofluorescent staining, which was particularly intense in or adjacent to nonparenchymal cells, but not in the parenchymal cells of this tissue. Quantitative analysis of fractions enriched in these cell populations corroborated the immunofluorescent data, although the relative amounts detected in response to zymosan treatment was greatly reduced compared to whole liver tissue. These results demonstrate the high specificity of the newly developed antibody and its usefulness in Western blot and immunohistochemical analysis for NTyr, confirm the presence of NTyr by complementary methods, and suggest the possible involvement of reactive nitrogen oxides in hepatic vascular dysfunction.

[Juxta-facet cysts: magnetic resonance tomography diagnosis]

The term juxta-facet cyst summarizes synovial cysts, arising from degenerated facet joints and ganglion cysts, developing from mucinous degeneration of periarticular connective tissue. Most juxta-facet cysts are observed at the L4/5 level, which generally has the most motion within the lumbar spine. In this retrospective study 31 juxta-facet cysts in 28 patients were detected within 2898 lumbar MRI studies over a 2-year period (frequency 1%). 24 patients complained of back and lower extremity pain, the other 4 patients had unilateral back pain. In 7 cases radicular symptoms were observed, in 6 patients a neurogenic claudication. In 78% of the patients juxta-facet cysts were responsible for clinical symptoms. MRI is the diagnostic imaging technique of choice due to a high sensitivity. The juxta-facet cysts were located extradural, laterally to the thecal sack and adjacent to a degenerated facet joint. In all but one cases the cysts showed a signal intensity equivalent to cerebrospinal fluid. T2-weighted pulse sequences in sagittal orientation were very useful in delineating the hypointense cyst wall. In 1 patient with acute radicular pain MRI demonstrated a subacute hemorrhage within a juxta-facet cyst. Calcifications and gas-filled cysts can be missed with MRI, but will be demonstrated by computed tomography. 45% of the juxta-facet cysts showed an enhancement of the cyst wall after injection of Gd-DTPA. Spontaneous reduction or resolution of the cyst may occur during rest. Injection of corticosteroids into the corresponding facet joint may reduce the inflammatory process and resolve the symptoms in up to 70%. Surgical resection of the cyst is indicated in case of intractable pain and significant neurologic deficit and generally produces good relief from radicular symptoms.

Comparison of color-flow Doppler scanning, power Doppler scanning, and frequency shift for assessment of carotid artery stenosis

OBJECTIVE

We investigated the accuracy of color-flow Doppler (CD) scanning, power Doppler (PD) scanning, and peak systolic Doppler frequency shift (PSF) in assessment of carotid artery stenosis with angiography used as gold standard, including the measurement techniques used in the North American Symptomatic Carotid Surgery Trial (NASCET) and the European Carotid Surgery Trial (ECST).

METHODS

Fifty-eight consecutive patients diagnosed for carotid artery surgery underwent color-coded duplex sonography and angiography. The duplex examination included the assessment of PSF and the videotaping of sagittal images in CD and PD mode from the proximal common carotid artery to the distal internal carotid artery. Two experienced examiners performed the studies, but once one examiner had done the taping, the other examiner was allowed only to review the tape. Separately, each examiner reviewed the tapes and determined by cursor settings each stenosis according to NASCET and ECST. For interobserver agreement kappa statistic was used. To compare with angiography (degree of stenosis 40%, 50%, 60%, 70%, and 80%) sensitivity, specificity, positive and negative predictive values, and overall accuracy were calculated. PSF cut-off frequencies were based on receiver operator curve analysis.

RESULTS

Because interobserver agreement in CD and PD was good (chance-corrected kappa > 0.6), further analysis used the between-observer mean value for each stenosis. With the NASCET measurement technique, accuracy of Doppler techniques to distinguish a 50% stenosis was 89% for PSF, 91% for CD, and 93% for PD; for a 70% stenosis it was 83% for PSF, 84% for CD, and 81% for PD. With the ECST measurement technique, accuracy to distinguish a 70% stenosis was 86% for PSF, 88% for CD, and 86% for PD; for an 80% stenosis it was 87% for PSF, 87% for CD, and 77% for PD.

CONCLUSION

CD and PD carotid artery stenosis measurements are highly reproducible, and in our hands provided accuracy equal to PSF.

GSK-3 inhibition by adenoviral FRAT1 overexpression is neuroprotective and induces Tau dephosphorylation and beta-catenin stabilisation without elevation of glycogen synthase activity

Glycogen synthase kinase 3 (GSK-3) has previously been shown to play an important role in the regulation of apoptosis. However, the nature of GSK-3 effector pathways that are relevant to neuroprotection remains poorly defined. Here, we have compared neuroprotection resulting from modulation of GSK-3 activity in PC12 cells using either selective small molecule ATP-competitive GSK-3 inhibitors (SB-216763 and SB-415286), or adenovirus overexpressing frequently rearranged in advanced T-cell lymphomas 1 (FRAT1), a protein proposed as a negative regulator of GSK-3 activity towards Axin and beta-catenin. Our data demonstrate that cellular overexpression of FRAT1 is sufficient to confer neuroprotection and correlates with inhibition of GSK-3 activity towards Tau and beta-catenin, but not modulation of glycogen synthase (GS) activity. By comparison, treatment with SB-216763 and SB-415286 proved more potent in terms of neuroprotection, and correlated with inhibition of GSK-3 activity towards GS in addition to Tau and beta-catenin.

Uncoupling protein-2 negatively regulates insulin secretion and is a major link between obesity, beta cell dysfunction, and type 2 diabetes

beta cells sense glucose through its metabolism and the resulting increase in ATP, which subsequently stimulates insulin secretion. Uncoupling protein-2 (UCP2) mediates mitochondrial proton leak, decreasing ATP production. In the present study, we assessed UCP2's role in regulating insulin secretion. UCP2-deficient mice had higher islet ATP levels and increased glucose-stimulated insulin secretion, establishing that UCP2 negatively regulates insulin secretion. Of pathophysiologic significance, UCP2 was markedly upregulated in islets of ob/ob mice, a model of obesity-induced diabetes. Importantly, ob/ob mice lacking UCP2 had restored first-phase insulin secretion, increased serum insulin levels, and greatly decreased levels of glycemia. These results establish UCP2 as a key component of beta cell glucose sensing, and as a critical link between obesity, beta cell dysfunction, and type 2 diabetes.

Cloning and functional characterization of an uncoupling protein homolog in hummingbirds

The cDNA of an uncoupling protein (UCP) homolog has been cloned from the swallow-tailed hummingbird, Eupetomena macroura. The hummingbird uncoupling protein (HmUCP) cDNA was amplified from pectoral muscle (flight muscle) using RT-PCR and primers for conserved domains of various known UCP homologs. The rapid amplification of cDNA ends (RACE) method was used to complete the cloning of the 5' and 3' ends of the open reading frame. The HmUCP coding region contains 915 nucleotides, and the deduced protein sequence consists of 304 amino acids, being approximately 72, 70, and 55% identical to human UCP3, UCP2, and UCP1, respectively. The uncoupling activity of this novel protein was characterized in yeast. In this expression system, the 12CA5-tagged HmUCP fusion protein was detected by Western blot in the enriched mitochondrial fraction. Similarly to rat UCP1, HmUCP decreased the mitochondrial membrane potential as measured in whole yeast by uptake of the fluorescent potential-sensitive dye 3',3-dihexyloxacarbocyanine iodide. The HmUCP mRNA is primarily expressed in skeletal muscle, but high levels can also be detected in heart and liver, as assessed by Northern blot analysis. Lowering the room's temperature to 12-14 degrees C triggered the cycle torpor/rewarming, typical of hummingbirds. Both in the pectoral muscle and heart, HmUCP mRNA levels were 1.5- to 3.4-fold higher during torpor. In conclusion, this is the first report of an UCP homolog in birds. The data indicate that HmUCP has the potential to function as an UCP and could play a thermogenic role during rewarming.