Effects of pulsed electromagnetic fields on cognitive processes - a pilot study on pulsed field interference with cognitive regeneration

BACKGROUND: Due to the ubiquitous use of cellular phones much has been speculated on secondary effects of electromagnetic irradiation emitted by those. Additionally, several studies have reported vegetative alterations as well as effects on the neuronal and molecular levels in humans. Here, using a psycho-physiological test paradigm, we examined effects of exposure to pulsed electromagnetic fields on cognitive performance. MATERIALS AND METHODS: In 11 volunteers, we tested cognitive processing under field exposure (GSM standard) and under field-free conditions. To examine the hypothesized effect of pulsed fields, we applied an auditory discrimination task and determined the participant's current 'Order Threshold' value. Following a first test cycle, the volunteers had to relax for 50 min while being, or not, exposed to pulsed electromagnetic fields. Subsequently, the test was repeated. Data acquired before and after the resting phase were compared from both experimental conditions. RESULTS: We found that nine of the 11 test participants (81.8%) showed worse results in their auditory discrimination performance upon field exposure as compared with control conditions. Group data comparison revealed a statistical significance of P = 0.0105. CONCLUSION: We could show that the participants' cognitive performance was impaired after exposure to pulsed electromagnetic fields. With regard to this finding, we recommend that the use of cellular phones should be restricted generally and in particular in respect of physical hazard of high-risk groups, e.g. elderly, children and ill people.     

Assessing student reflection in medical practice. The development of an observer-rated instrument: reliability, validity and initial experiences

INTRODUCTION: This study describes the development of an instrument to measure the ability of medical students to reflect on their performance in medical practice. METHODS: A total of 195 Year 4 medical students attending a 9-hour clinical ethics course filled in a semi-structured questionnaire consisting of reflection-evoking case vignettes. Two independent raters scored their answers. Respondents were scored on a 10-point scale for overall reflection score and on a scale of 0-2 for the extent to which they mentioned a series of perspectives in their reflections. We analysed the distribution of scores, the internal validity and the effect of being pre-tested with an alternate form of the test on the scores. The relationships between overall reflection score and perspective score, and between overall reflection score and gender, career preference and work experience were also calculated. RESULTS: The interrater reliability was sufficient. The range of scores on overall reflection was large (1-10), with a mean reflection score of 4.5-4.7 for each case vignette. This means that only 1 or 2 perspectives were mentioned, and hardly any weighing of perspectives took place. The values over the 2 measurements were comparable and were strongly related. Women had slightly higher scores than men, as had students with work experience in health care, and students considering general practice as a career. CONCLUSIONS: Reflection in medical practice can be measured using this semistructured questionnaire built on case vignettes. The mean score allows for the measurement of improvement by future educational efforts. The wide range of individual differences allows for comparisons between groups. The differences found between groups of students were as expected and support the validity of the instrument.     

Using accountability to improve reproductive health care

Accountability is best understood as a referee of the dynamics in two-way relationships, often between unequal partners. The literature on accountability distinguishes between political, fiscal, administrative, legal and constitutional accountability. This paper focuses on accountability mechanisms in health care and how they mediate between service providers and communities and between different kinds of health personnel at the primary health care level. It refers to case studies of participatory processes for improving sexual and reproductive health service delivery. Information, dialogue and negotiation are important elements that enable accountability mechanisms to address problems by supporting change and engagement between participants. In order to succeed, however, efforts towards better accountability that broaden the participation of users must take into account the social contexts and the policy and service delivery systems in which they are applied, address power relations and improve the representation of marginalised groups within communities and service delivery systems.     

Involvement of Gas7 in nerve growth factor-independent and dependent cell processes in PC12 cells

Gas7, a growth arrest-specific gene originally isolated from serum-starved mouse fibroblast cells, is expressed in vivo predominantly in the brain and is required for neurite formation in cultured mouse cerebellar neurons (Ju et al. [1998] Proc. Natl. Acad. Sci. USA 95: 11423-11428). Here we report that Gas7 plays a key role in the morphological differentiation of PC12 preneuronal rat pheochromocytoma cells (PC12 cells). We found that overexpression of murine Gas7 in PC12 cells leads to an expanded cell morphology and promotes spike-like cell processes that resemble the early stages of neurite formation. These processes undergo elongation upon addition of nerve growth factor (NGF). We also found that the addition of NGF induces the production of endogenous rat-Gas7 (rGas7), which is transiently elevated prior to the appearance of NGF-promoted neurite outgrowths. Furthermore, inhibition of endogenous rGas7 production by antisense nucleotides complimentary to the translation initiation region of a rGas7 cDNA (AJ131902) reduces the NGF-promoted neurite outgrowths. Our results demonstrate that Gas7 by itself influences early cell morphological development and likely functions as an early-stage intermediary in NGF-induced neuronal differentiation of PC12 culture cells.     

Making psychiatric epidemiology useful: the contribution of epidemiology to government policy

OBJECTIVE: This paper aims to discuss the contribution of epidemiology to aspects of public policy that have either a direct influence on mental health and mental disorders, or an indirect effect by influencing environmental factors which influence mental health. Both kinds of public policy will need to be considered by governments wishing to protect, promote and improve the mental health of their populations. The paper draws on information from both relatively wealthy and low-income countries. METHOD: The paper defines epidemiology and mental health policy, sets out the range of government policies which may have an impact on mental health, and explores the ways in which epidemiology may contribute to mental health policy in relation to service inputs, processes and outcomes as well as to wider government policies. The paper also examines the advantages and disadvantages of different sources of data. RESULTS: There are a number of reasons to carry out large-scale surveys of psychiatric morbidity. First, effective policy should address the needs of the population, which can best be assessed by the epidemiology and the social and economic causes and consequences of psychiatric morbidity. Secondly, representative information in a defined geographic area can document the use of existing services and can estimate the extent of unmet needs and the services required meeting those needs. Thirdly, valid information on prevalence and associated risk factors of presumed causal importance allow aetiological hypotheses to be generated and tested and models developed for prevention. Finally, by repeating community surveys, it is possible to monitor the health of the population and trends. Epidemiological findings emphasize the importance of mental health policy addressing the key role of primary care, the social context and social consequences of disorder, the importance of addressing services for children, the need to reduce premature mortality from suicide and from physical illness. Epidemiological findings show that mental health and mental disorders are related to the environment both in its structural physical sense and in the sense of the social processes connected to and influenced by particular settings. Thus epidemiology can contribute to general policies on employment and unemployment, housing and homelessness, education and women's issues. CONCLUSION: Mental health policy is increasingly recognized as an essential area for countries wishing to enhance their economic, social and human capital. Epidemiological data are a basic prerequisite to informing such policies. Expert professional and epidemiological advice to ministries is essential if policy is to be rooted in the evidence for population needs, risk factors, effective treatments and services, and measurement of outcomes. It is therefore important to develop the capacity for policy work in the psychiatric profession by including public health, epidemiology and policy placements for young psychiatrists.     

Analysis of postural sway using entropy measures of signal complexity

A stochastic complexity analysis is applied to centre-of-pressure (COP) time series, by using different complexity features, namely the spectral entropy, the approximate entropy, and the singular value decomposition spectrum entropy. A principal component analysis allows an estimate of the overall signal complexity in terms of the ensemble complexity score; the difference in values between open-eyes (OE) and closed-eyes (CE) trials is used for clustering purposes. In experiments on healthy young adults, the complexity of the mediolateral component is shown not to depend on the manipulation of vision. Conversely, the increase of the anteroposterior complexity in OE conditions can be statistically significant, leading to a functional division of the subjects into two groups: the Romberg ratios (RRs), namely the ratios of the CE measure to the OE measure, are: RR=1.19±0.15 (group 1 subjects), and RR=1.05±0.14 (group 2 subjects). Multivariate statistical techniques are applied to the complexity features and the parameters of a postural sway model recently proposed; the results suggest that the complexity change is the sign of information-generating behaviours of postural fluctuations, in the presence of a control strategy which aims at loosening long-range correlation and decreasing stochastic activity when visual feedback is allowed.     

Culture and purification of human fetal olfactory ensheathing cells using different attachment rates combined with intermittent NT3 nutrition

Objective：To explore a simple and pragmatic method to obtain sufficient olfactory ensheathing cells from human fetus by selective attachment of harvested cells combined with intermittent NT3 nutrition. Methods：DMEM/F12 culture solution including 10% fetal bovine serum or NT3 was used to culture olfactory ensheathing cells intermittently every 48 h. The cell state and growth rates of OECs were observed, and P75 staining was used to estimate the purity of the cells. Results：Human fetal OECs were positive with P75 immunocytochemical staining. OECs in dipolar or tripolar shape formed networks by their processes in vitro. The purity of OECs in ＂good state＂ was about 95% at 9 d and 83% on 12 d, respectively. Conclusion：The method of using different attachment rates combined with intermittent NT3 addition is a simple and effective way to culture and purify OECs.     

Neuronal expression of Nogo-A mRNA and protein during neurite outgrowth in the developing rat olfactory system

The major impediments to axonal regeneration in the central nervous system are growth-inhibitory proteins present in the myelin sheath, and Nogo-A is one of the most potent inhibitors synthesized by oligodendrocytes. However, neuronal expression of Nogo-A during development suggests that it may have an additional role. The spatio-temporal regulation of both Nogo-A mRNA and protein expression was examined by in situ hybridization and immunohistochemistry in the developing rat olfactory system. During embryonic and postnatal development (from E13 to P6), Nogo-A mRNA and protein were strongly expressed by differentiating neurons in the olfactory epithelium and in the olfactory bulb. From the second postnatal week, a progressive down-regulation of both Nogo-A mRNA and protein occurred, such that only a weak expression persisted in the adult olfactory system. Using double-immunostainings in the adult olfactory epithelium, we determined that Nogo-A was preferentially expressed by immature olfactory receptor neurons extending axonal processes toward the olfactory bulb. At all developmental stages, Nogo-A protein was preferentially targeted in olfactory axons emerging from the olfactory epithelium. Using an in vitro model of olfactory axon growth, we demonstrated that, in addition to its presence along the entire axon length, Nogo-A accumulated in axonal growth cone and at axonal branching points, with a distribution similar to that of microtubule-associated proteins. Moreover, Nogo-A was transiently expressed in dendritic processes in the postnatal olfactory bulb. Together, our data suggest that, in non-pathological conditions, Nogo-A may be involved in the processes of axonal growth and dendritic modeling through the regulation of microtubule dynamics.     

Relevance of EEG alpha and theta oscillations during task switching

In a task switching design, we investigated the question whether long-range theta coupling primarily reflects top–down control processes. Switch and stay trials did not differ with respect to memory load or global working memory (WM) demands. The results revealed significantly stronger theta coupling (in a range of 4–7 Hz) between prefrontal and posterior regions during switch as compared to stay trials. Power differences, reflecting more local effects, were largest in the upper alpha band (10–13 Hz) and over posterior brain areas, possibly reflecting long-term memory activation. The conclusion of the present study is that long-range coherent oscillatory activity in the theta band reflects top–down activation rather than global WM functions.     

Efficient Up-Conversion ZnO Co-Doped (Er,Yb) Nanopowders Synthesized via the Sol-Gel Process for Photovoltaic Applications

In this study, undoped and (Erbium, Ytterbium) co-doped ZnO nanopowders were prepared using the sol-gel method and the supercritical drying of ethyl alcohol. Doping ZnO nanopowders were elaborated with 5 mol% of Er (5 Er: ZnO), 5 mol% of Er and 5 mol% of Yb (5 Er, 5 Yb: ZnO), and 5 mol% of Er and 10 mol% of Yb (5 Er, 10 Yb: ZnO) concentrations. The effects of the Yb concentration on the structural, morphological, photoluminescent, and electrical properties of the ZnO nanopowders were investigated. The main findings of this work were the crystallinization of all of the nanopowders in a hexagonal Wurtzite structure with a spheroidal morphology and a size of 60 nm. Hence, the doping concentration would affect the crystallinity and the morphology of the ZnO nanopowder. The UC (Up-Conversion) emissions were investigated under a 980 nm excitation. It was observed that (Er, Yb: ZnO) exhibited green, ranging between 525 nm and 550 nm and red up-converted emissions of 655 nm, due to the efficient energy transfer process between Er³⁺ and Yb³⁺. The absolute quantum yield percentage (QY %) of the doped nanopowders was measured as a function of power density at each up-converted emission. This would prove that (5 Er, 5 Yb: ZnO) had the highest QY percentage value of 6.31 ± 0.2% at a power density of 15.7 W/cm². Additionally, it had the highest excited state lifetime for green and red emissions. Moreover, the Hall effect measures showed that the resistivity decreased while the electron mobility increased after doping, suggesting that most of rare earth ions were located in the interstitial positions. The carrier concentration increased after doping until (5 Er, 5 Yb: ZnO), suggesting that the Zn²⁺ ions substituted the RE³⁺ ions. Then, the carrier concentration decreased, suggesting that doping with higher concentrations would cause grain boundary defects. These findings would suggest that (5 Er, 5 Yb: ZnO) would have the best electrical properties and the lowest band gap energy (3.24 eV). Therefore, the presented preparation of the (Er, Yb: ZnO) nanopowders elaborated, using the sol-gel process would be a potential interesting material for UC applications.