Optimization of pulse train presaturation for CEST imaging in clinical scanners

Chemical exchange saturation transfer (CEST) imaging depends on the performance of radiofrequency saturation during the experiment. Scanner specifications, in particular limited pulse width and duty‐cycle, and specific absorption rate guidelines restrict the full exploitation of CEST effects in clinical MR systems. The purpose of this study was to optimize techniques for effective pulse train presaturation for CEST imaging in a whole‐body MR scanner. Theoretical analysis and simulations of the spectral properties of radiofrequency pulse trains demonstrated the significance of pulse width τ_P and interpulse delay τ_D for effective and selective labeling of a chemically exchanging proton pool. CEST experiments with model solutions, e.g., creatine dissolved in water, showed best performance of pulse trains with τ_P = τ_D = 100 msec, regarding minimum direct water saturation in z‐spectra and distinct magnetization transfer ratio asymmetry that can be determined quantitatively. Saturation efficiency of trains of Gaussian‐shaped radiofrequency pulses using this timing was evaluated in MR imagers with field strengths of 1.5, 3, and 7 T. The proposed saturation pulse train does not require hardware modifications, offers low specific absorption rate, and can be used in a standard clinical setup. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

加快寄防人才培养促进寄防事业发展

针对寄生虫病防治及人才队伍的现状,提出了加强专业教育、搞好在岗培训、提倡以老带新和鼓励在职自学等措施来加快寄防人才培养,促进寄防事业的发展。     

择时针刺治疗乳腺增生症的思路与方法

通过详细介绍月经周期中的择时治疗及纳甲法、纳子法的开穴原理,探讨择时针刺治疗乳腺增生症的思路与方法,从而指导乳腺增生症的临床针刺治疗.     

普通肝素治疗不稳定性心绞痛72例疗效观察

目的观察普通肝素治疗不稳定性心绞痛的疗效及安全性。方法对72例使用普通肝素抗凝的不稳定性心绞痛患者的临床资料进行回顾性分析。结果本组72例中,显著疗效55例（76.39%）,有效13例（18.01%）无效4例（5.6%）。结论普通肝素由于经静脉注射,具有起效快、疗效确切的优点,且费用低廉,在不稳定性心绞痛抗凝治疗中可以作为首选用药。     

NeuroQuest: a comprehensive analysis tool for extracellular neural ensemble recordings

Analyzing the massive amounts of neural data collected using microelectrodes to extract biologically relevant information is a major challenge. Many scientific findings rest on the ability to overcome these challenges and to standardize experimental analysis across labs. This can be facilitated in part through comprehensive, efficient and practical software tools disseminated to the community at large. We have developed a comprehensive, MATLAB-based software package - entitled NeuroQuest - that bundles together a number of advanced neural signal processing algorithms in a user-friendly environment. Results demonstrate the efficiency and reliability of the software compared to other software packages, and versatility over a wide range of experimental conditions.     

Bursting as a source of non‐linear determinism in the firing patterns of nigral dopamine neurons

Nigral dopamine (DA) neurons in vivo exhibit complex firing patterns consisting of tonic single‐spikes and phasic bursts that encode information for certain types of reward‐related learning and behavior. Non‐linear dynamical analysis has previously demonstrated the presence of a non‐linear deterministic structure in complex firing patterns of DA neurons, yet the origin of this non‐linear determinism remains unknown. In this study, we hypothesized that bursting activity is the primary source of non‐linear determinism in the firing patterns of DA neurons. To test this hypothesis, we investigated the dimension complexity of inter‐spike interval data recorded in vivo from bursting and non‐bursting DA neurons in the chloral hydrate‐anesthetized rat substantia nigra. We found that bursting DA neurons exhibited non‐linear determinism in their firing patterns, whereas non‐bursting DA neurons showed truly stochastic firing patterns. Determinism was also detected in the isolated burst and inter‐burst interval data extracted from firing patterns of bursting neurons. Moreover, less bursting DA neurons in halothane‐anesthetized rats exhibited higher dimensional spiking dynamics than do more bursting DA neurons in chloral hydrate‐anesthetized rats. These results strongly indicate that bursting activity is the main source of low‐dimensional, non‐linear determinism in the firing patterns of DA neurons. This finding furthermore suggests that bursts are the likely carriers of meaningful information in the firing activities of DA neurons.     

铁路旅客对艾滋病知识意识以及需求状况调查

目的 了解铁路旅客对艾滋病知识水平、意识以及需求状况. 方法 采用多阶段抽样的方法,对北京等七个铁路局管辖的数十辆列车上的11 146名旅客进行调查. 结果 93.9%的调查对象听说过艾滋病,但对相关知识的知晓率较低.几乎所有的调查对象都表示对艾滋病知识有需求,其中对预防措施的需求最高.广播是旅客选择最多的宣传方式....     

Disfunção sistólica ventricular esquerda detetada por speckle tracking em hipertensos com fração de ejeção preservada

Introduction The spectrum of hypertensive heart disease is wide, and can include left ventricular dysfunction. The development of echocardiographic parameters to improve patient stratification and to identify early adverse changes could be clinically useful.Aim To identify subclinical left ventricular dysfunction in hypertensive subjects with preserved ejection fraction (>55%), identified by global parameters of myocardial strain on speckle tracking imaging.Methods This was a comparative observational study of two groups of individuals: normotensive (n=20, age 59±7 years, 55% male) and hypertensive (n=229, age 62±12 years, 57% male). Left ventricular function was assessed by various conventional clinical and echocardiographic parameters and global longitudinal and circumferential myocardial strain. Cut-off values to detect subclinical left ventricular dysfunction were established and applied in the hypertensive group. The Student's t test, Mann-Whitney test and chi-square test were used for the comparative statistical analysis.Results Most hypertensive subjects (53.7%) had grade I hypertension; blood pressure was controlled in 64.9%, and 54.8% showed left ventricular structural changes. Comparison between the normotensive and hypertensive groups showed no significant differences in parameters of global longitudinal or circumferential systolic strain. Application of the cut-offs to the hypertensive group identified 35 individuals (15.3%) as having subclinical left ventricular systolic dysfunction as assessed by global longitudinal myocardial strain parameters.Conclusions In this group of hypertensive patients, global myocardial strain parameters identified a group of individuals with subclinical left ventricular systolic dysfunction despite preserved ejection fraction. The clinical relevance of these findings needs to be assessed in long-term follow-up studies.     

Cardiovascular reaction to job stress in middle-aged train drivers

In this study, cardiovascular (CV) response to a standard laboratory challenge was compared to 24-hr noninvasive monitoring of heart rate (HR) and blood pressure (BP) in 30 healthy middle-aged train drivers. Laboratory stress test consisted of the orthostatic test, the cold pressor test, the Valsalva maneuver, the Stroop test, and the numerical square. In addition, the participants completed an extensive questionnaire on their health state and family health history, lifestyle, job stress, social and family support, personality characteristics, and health risk behaviors. In waking activities (leisure time, traveling to work, preparations for driving, and an uneventful driving) HR and systolic Wood pressure (SBP), but not diastolic Wood pressure (DBP), were normal (e.g., mean HR = 78.3, SBP = 128.6. and DBP= 92.3 during driving). In occasional stressful work situations, most participants reacted with a considerable rise in SBP and DBP (maximum values 201 for SBP and 126 for DBP). Interindividual differences in maximum BP reactions to emergency stress were predicted reliably by several psychological characteristics and by the CV reactions to the laboratory psychological challenge. The frequency, intensity, and persistence of psychological and physiological reactions to urgent situations appear to be more relevant measures of the health impact of psychological job stress than are the shift average values of physiological stress markers.     

The effect of an irregular shift system on sleepiness at work in train drivers and railway traffic controllers

Sleepiness and fatigue are frequent problems in railway transportation with occasional monotony and irregular shift schedules. This study aimed at (1) studying the prevalence of severe sleepiness in shifts and (2) examining which shift and sleep-related factors were associated with the occurrence of severe sleepiness in an irregular shift system. A total of 126 randomly selected male train drivers (Tdrs) and 104 railway traffic controllers (Tcos) were investigated using questionnaires and sleep-wake diaries. A sleep diary was used to collect information on sleepiness at work and sleeping times during the 21 consecutive days of the study. The prevalence of severe sleepiness at work (i.e. Karolinska Sleepiness Scale 7 or higher) was modelled by a logistic regression analysis for repeated measurements (GEE) using different shift schedule related factors and sleep length as explanatory variables. Severe sleepiness was reported in 49% (Tdrs) and 50% (Tcos) of the night shifts and in 20% (Tdrs) and 15% (Tcos) of the morning shifts. The odds ratios showed that the risk for severe sleepiness was 6-14 times higher in the night shift and about twice as high in the morning shift compared with the day shift. Age affected the two occupational samples differently: with Tdrs increased age was associated with an additional 8% reduction of risk for severe sleepiness for each year of age, while the Tcos did not show any age dependency. Shift length increased the risk by 15% for each hour of the shift and main sleep period decreased the risk by 15% for each hour of the main sleep. The risk of severe sleepiness was not consistently related to the time-off period before the shifts. The results indicate that adjustments for shift timing, length and off-duty time, in addition to actions aiming at extending the main sleep period, would probably decrease severe sleepiness in railway transportation.