受孕龄28～30周早产儿脑电图高幅慢波改变对其预后的评估价值及临床意义

目的 观察受孕龄(conceptional age,CA) 28～ 30周早产儿脑电图高幅慢波改变情况,探讨其对早产儿预后的评估价值及临床意义.方法 2011年8月至2012年5月我院新生儿重症监护病房收治受孕龄28～30周早产儿34例,于生后1～3d进行床旁视频脑电图(video electroencephalogram,VEEG)监测,根据受孕龄将受监测者分为受孕龄28～ 29周及30周2个观察组,根据随访结果又将2个观察组细分为死亡组和存活组,各12例,对每份VEEG记录的暴发间隔时间(interburst interval duration,IBI)及高幅慢波进行20 min半定量分析.结果 死亡组与存活组比较,最大IBI时程在受孕龄28 ～ 29周及30周均差异显著(P＜0.01)；高幅慢波主要分布于颞、枕区,形态以光滑δ波占优势,其次为δ刷,波幅以150～300 μV为主,在该波幅段优势空间分布及优势波形分布无差异,＞300 μV慢波在死亡组中数量高于存活组,在空间分布上于颞、枕及前额区有差异(P＜0.05),在形态上重叠多高尖波的δ波分布差异最为显著(P＜0.01),其次为尖样δ波和δ刷(P＜0.05)；畸形δ刷、畸形δ波中重叠多高尖波的δ波和一般畸形δ波在死亡组中的发生率均高于存活组(P＜0.05).结论 早产儿早期床旁VEEG中IBI时程过长及特殊形态的畸形高幅慢波过多提示脑损伤和/或预后不良发生可能.     

Exploring the radiosensitizing potential of magnetotherapy: a pilot study in breast cancer cells

Abstract

Aim: To explore the influence of electromagnetic fields (EMFs) on the cell cycle progression of MDA-MB-231 and MCF-7 breast cancer cell lines and to evaluate the radiosensitizing effect of magnetotherapy during therapeutic co-exposure to EMFs and radiotherapy.

Material and methods: Cells were exposed to EMFs (25, 50 and 100?Hz; 8 and 10?mT). In the co-treatment, cells were first exposed to EMFs (50?Hz/10?mT) for 30?min and then to ionizing radiation (IR) (2?Gy) 4?h later. Cell cycle progression and free radical production were evaluated by flow cytometry, while radiosensitivity was explored by colony formation assay.

Results: Generalized G1-phase arrest was found in both cell lines several hours after EMF exposure. Interestingly, a marked G1-phase delay was observed at 4?h after exposure to 50?Hz/10?mT EMFs. No cell cycle perturbation was observed after repeated exposure to EMFs. IR-derived ROS production was enhanced in EMF-exposed MCF-7 cells at 24?h post-exposure. EMF-exposed cells were more radiosensitive in comparison to sham-exposed cells.

Conclusions: These results highlight the potential benefits of concomitant treatment with magnetotherapy before radiotherapy sessions to enhance the effectiveness of breast cancer therapy. Further studies are warranted to identify the subset(s) of patients who would benefit from this multimodal treatment.     

High‐permittivity solid ceramic resonators for high‐field human MRI

The properties of a ceramic‐based annular dielectric resonator designed for 7 T MRI have been examined. Electromagnetic simulations and experimentally determined modal frequencies agree to within ~1%. The dependence of the resonance frequency of the degenerate quadrature HEM₁₁ modes on hole diameter and shield diameter was also investigated. The constructed coil, with a 2.5 cm diameter hole, had an unloaded Q value of 400, which was reduced to 150 when loaded with a human finger. Simulated and experimental B₁⁺ maps show a high degree of homogeneity with a sensitivity of ~11.5 μT/√W at the centre. A comparison with a loop gap resonator showed an approximately 25% higher sensitivity for the dielectric resonator. High‐resolution images of the digital interphalangeal (DIP) and proximal interphalangeal (PIP) joints of volunteers were acquired in imaging times of less than 2 min. Finally, novel methods of double tuning such ceramic resonators to two relatively close frequencies, e.g. proton and fluorine, have been shown. Copyright © 2013 John Wiley & Sons, Ltd.     

Implantable rhythm devices and electromagnetic interference: myth or reality?

Current medical guidelines have prompted implementation of increasing numbers of implantable rhythm devices, be they pacemakers, internal cardioverter–defibrillators or loop recorders. These devices rely on complex microcircuitry and use electromagnetic waves for communication. They are, therefore, susceptible to interference from surrounding electromagnetic radiation and magnetic energy. Hermetic shielding in metallic cases, filters, interference rejection circuits and bipolar sensing have contributed to their relative resistance to electromagnetic interference (EMI) in household and workplace environments. Device interactions have occurred in hospitals where EMI sources are ubiquitous, including radiation, electrocautery and MRI exposures. However, with rapidly evolving technology, devices and potential sources of EMI continue to change. This review provides a contemporary overview of the current state of knowledge regarding risks attributable to EMI; highlights current limitations of implantable rhythm devices; and attempts to distinguish myths from realities.     

Brain Cancer Risk and Electromagnetic Fields (EMFs): Assessing the Geomagnetic Component

Cancer cluster studies in North Carolina identified several communities in which there existed an elevated risk of brain cancer. These findings prompted a series of case-control studies. The current article, which originated from the results of the 3rd of such studies, is focused on inclusion of the earth's own geomagnetic fields that interact with electromagnetic fields generated from distribution power lines. This article also contains an assessment of the contribution of confounding by residential (e.g., urban, rural) and case characteristics (e.g., age, race, gender). Newly diagnosed brain cancer cases were identified for a 4-county region of central North Carolina, which the authors chose on the basis of the results of earlier observations. A 3:1 matched series of cancer cases from the same hospitals in which the cases were diagnosed served as the comparison group. Extensive geographic information was collected and was based on an exact place of residence at the time of cancer diagnosis, thus providing several strategic geophysical elements for assessment. The model for this assessment was based on the effects of these two sources of electromagnetic fields for an ion cyclotron resonance mechanism of disease risk. The authors used logistic regression models that contained the predicted value for the parallel component of the earth's magnetic field; these models were somewhat erratic, and the elements were not merged productively into a single statistical model. Interpretation of these values was difficult; therefore, the modeled values for the model elements, at progressive distances from the nearest power-line segments, are provided. The results of this study demonstrate the merits of using large, population-based databases, as well as using rigorous Geographic Information System techniques, for the assessment of ecologic environmental risks. The results also suggest promise for exposure classification that is compatible with the theoretical biological mechanisms posited for electromagnetic fields.     

Stimuli-responsive liposome-nanoparticle assemblies

Introduction: Nanoscale assemblies are needed that achieve multiple therapeutic objectives, including cellular targeting, imaging, diagnostics and drug delivery. These must exhibit high stability, bioavailability and biocompatibility, while maintaining or enhancing the inherent activity of the therapeutic cargo. Liposome-nanoparticle assemblies (LNAs) combine the demonstrated potential of liposome-based therapies, with functional nanoparticles. Specifically, LNAs can be used to concentrate and shield the nanoparticles and, in turn, stimuli-responsive nanoparticles that respond to external fields can be used to control liposomal release. The ability to design LNAs via nanoparticle encapsulation, decoration or bilayer-embedment offers a range of configurations with different structures and functions.

Areas covered: This paper reviews the current state of research and understanding of the design, characterization and performance of LNAs. A brief overview is provided on liposomes and nanoparticles for therapeutic applications, followed by a discussion of the opportunities and challenges associated with combining the two in a single assembly to achieve controlled release via light or radiofrequency stimuli.

Expert opinion: LNAs offer a unique opportunity to combine the therapeutic properties of liposomes and nanoparticles. Liposomes act to concentrate small nanoparticles and shield nanoparticles from the immune system, while the nanoparticle can be used to initiate and control drug release when exposed to external stimuli. These properties provide a platform to achieve nanoparticle-controlled liposomal release. LNA design and application are still in infancy. Research concentrating on the relationships among LNA structure, function and performance is essential for the future clinical use of LNAs.     

On the optimal choice of the exposure conditions and the nanoparticle features in magnetic nanoparticle hyperthermia

Purpose: Two points are particularly relevant for the clinical use of magnetic nanoparticle hyperthermia: the optimisation of both the exposure conditions and the magnetic nanoparticle characteristics, and the assessment of the limits of scalability of the treatment. To answer these two points a criterion for the individuation of the magnetic field parameters and of the magnetic nanoparticle features that minimise the therapeutic concentration of nanoparticles to be used in magnetic nanoparticle hyperthermia is developed.

Methods: The proposed criterion is based on the estimation of the levels of heat generation rate, due to the electromagnetic field, to be supplied to both the cancerous and the neighbouring healthy tissues for achieving the therapeutic heating of the tumour with a desired degree of spatial selectivity. These quantities are determined by exploiting the Pennes bioheat transfer model.

Results: The reliability of the criterion has been proven by means of an extensive numerical analysis, performed by considering tumours of spherical shape embedded in tissues of cylindrical shape. Several cases, including tumours of different sizes and position have been considered.

Conclusions: By exploiting the proposed criterion a study of the clinical scalability of the therapeutic approach is presented.     

Abnormalities of resting-state EEG in patients with prodromal and overt dementia with Lewy bodies: Relation to clinical symptoms

ObjectiveHere we tested if cortical sources of resting state electroencephalographic (rsEEG) rhythms may differ in sub-groups of patients with prodromal and overt dementia with Lewy bodies (DLB) as a function of relevant clinical symptoms.MethodsWe extracted clinical, demographic and rsEEG datasets in matched DLB patients (N = 60) and control Alzheimer’s disease (AD, N = 60) and healthy elderly (Nold, N = 60) seniors from our international database. The eLORETA freeware was used to estimate cortical rsEEG sources.ResultsAs compared to the Nold group, the DLB and AD groups generally exhibited greater spatially distributed delta source activities (DLB > AD) and lower alpha source activities posteriorly (AD > DLB). As compared to the DLB “controls”, the DLB patients with (1) rapid eye movement (REM) sleep behavior disorders showed lower central alpha source activities (p < 0.005); (2) greater cognitive deficits exhibited higher parietal and central theta source activities as well as higher central, parietal, and occipital alpha source activities (p < 0.01); (3) visual hallucinations pointed to greater parietal delta source activities (p < 0.005).ConclusionsRelevant clinical features were associated with abnormalities in spatial and frequency features of rsEEG source activities in DLB patients.SignificanceThose features may be used as neurophysiological surrogate endpoints of clinical symptoms in DLB patients in future cross-validation prospective studies.