Lipid and fatty acid profiles in rats consuming different high-fat ketogenic diets

High-fat ketogenic diets are used to treat intractable seizures in children, but little is known of the mechanism by which these diets work or whether fats rich in n−3 polyunsaturates might be beneficial. Tissue lipid and fatty acid profiles were determined in rats consuming very high fat (80 weight%), low-carbohydrate ketogenic diets containing either medium-chain triglyceride, flaxseed oil, butter, or an equal combination of these three fat sources. Ketogenic diets containing butter markedly raised liver triglyceride but had no effect on plasma cholesterol. Unlike the other fats, flaxseed oil in the ketogenic diet did not raise brain cholesterol. Brain total and free fatty acid profiles remained similar in all groups, but there was an increase in the proportion of arachidonate in brain total lipids in the medium-chain triglyceride group, while the two groups consuming flaxseed oil had significantly lower arachidonate in brain, liver, and plasma. The very high dietary intake of α-linolenate in the flaxseed group did not change docosahexaenoate levels in the brain. Our previous report based on these diets showed that although ketosis is higher in rats consuming a ketogenic diet based on medium-chain triglyceride oil, seizure resistance in the pentylenetetrazol model is not clearly related to the degree of ketosis achieved. In combination with our present data from the same seizure study, it appears that ketogenic diets with widely differing effects on tissue lipids and fatty acid profiles can confer a similar amount of seizure protection.     

Insulin status-dependent alterations in lipid/phospholipid composition of rat kidney microsomes and mitochondria

Early and late effects of alloxan-diabetes on lipid/phospholipid composition in rat kidney microsomes and mitochondria were examined. In microsomes, early diabetic state resulted in an increase in contents of total phospholipids (TPL), cholesterol (CHL), with an increase in the lysophospholipids (Lyso), phosphatidylcholine (PC), and phosphatidylinositol (PI) components. The sphinogmyelin (SPM), phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidic acid (PA) content decreased. Treatment with insulin had no effect on PC but PE increased and the other components decreased. In the 1-month diabetic group PI, PS, PE, and PA components decreased, whereas Lyso and PC increased. Treatment with insulin had restorative effects on PE, PI, and PS; Lyso was further elevated whereas PA decreased. In mitochondria, at an early stage of diabetes marginally increased CHL content was restored by insulin treatment. Long-term diabetes lowered the TPL and elevated the CHL content. Treatment with insulin partially restored the TPL and CHL content. A diabetic state decreased the proportion of PE and diphosphatidylglycerol (DPG) components but increased the Lyso, SPM, PC, PI, and PS components in the mitochondria. Treatment with insulin had a partial restorative effect. The membrane fluidity of both microsomes and mitochondria decreased in general in the diabetic condition and was not corrected by insulin treatment at a late stage. However, at an early stage, treatment with insulin fluidized both membranes.     

IMPACT: a facility to study the interaction of low-energy intense particle beams with dynamic heterogeneous surfaces

The Interaction of Materials with Particles and Components Testing (IMPACT) experimental facility is furnished with multiple ion sources and in situ diagnostics to study the modification of surfaces undergoing physical, chemical, and electronic changes during exposure to energetic particle beams. Ion beams with energies in the range between 20 and 5000 eV can bombard samples at flux levels in the range of 10(10)-10(15) cm(-2) s(-1); parameters such as ion angle of incidence and exposed area are also controllable during the experiment. IMPACT has diagnostics that allow full characterization of the beam, including a Faraday cup, a beam imaging system, and a retarding field energy analyzer. IMPACT is equipped with multiple diagnostics, such as electron (Auger, photoelectron) and ion scattering spectroscopies that allow different probing depths of the sample to monitor compositional changes in multicomponent and/or layered targets. A unique real-time erosion diagnostic based on a dual quartz crystal microbalance measures deposition from an eroding surface with rates smaller than 0.01 nm/s, which can be converted to a sputter yield measurement. The monitoring crystal can be rotated and placed in the target position so that the deposited material on the quartz crystal oscillator surface can be characterized without transfer outside of the vacuum chamber.     

Ex-vivo cellular MRI with b-SSFP: quantitative benefits of 3 T over 1.5 T

INTRODUCTION: The use of MRI with iron-based magnetic nanoparticles for imaging cells is a rapidly growing field of research. We have recently reported that single iron-labeled cells could be detected, as signal voids, in vivo in mouse brains using a balanced steady-state free precession imaging sequence (b-SSFP) and a customized microimaging system at 1.5 T. METHODS: In the current study we assess the benefits, and challenges, of using a higher magnetic field strength for imaging iron-labeled cells with b-SSFP, using ex vivo mouse brain specimens imaged with near identical systems at 1.5 and 3.0 T. RESULTS: The substantial banding artifact that appears in 3 T b-SSFP images was readily minimized with RF phase cycling, allowing for banding-free b-SSFP images to be compared between the two field strengths. This study revealed that with an optimal 3 T b-SSFP imaging protocol, more than twice as many signal voids were detected as with 1.5 T. CONCLUSION: There are several factors that contributed to this important result. First, a greater-than-linear SNR gain was achieved in mouse brain images at 3 T. Second, a reduction in the bandwidth, and the associated increase in repetition time and SNR, produced a dramatic increase in the contrast generated by iron-labeled cells.     

SA-BFSN:一种自适应基于密度聚类的算法

针对BFSN算法需要人工输入参数r和λ的缺陷,提出了一种自适应确定r和λ的SA-BFSN聚类方法。该方法通过Inverse Gaussian拟合判断r参数,通过分析噪声点数量的分布特征选择合适的λ值。算法测试表明,使用SA-BFSN无需人工输入参数,能够实现聚类过程的全自动化,能够有效处理任意形状、大小和密度的簇。     

基于HSI空间模糊聚类的彩色图像分割新方法

模糊C均值(FCM)被广泛应用于彩色图像分割中,但传统的模糊C均值由于没有考虑空间信息,因此对噪声特别敏感。针对此问题,提出了一种在HIS颜色空间结合像素邻域空间信息的模糊聚类新方法。实验结果表明,此方法对高噪声图像有较好的处理结果。     

Asymptotic behaviors of support vector machines with Gaussian kernel

Support vector machines (SVMs) with the gaussian (RBF) kernel have been popular for practical use. Model selection in this class of SVMs involves two hyperparameters: the penalty parameter C and the kernel width sigma. This letter analyzes the behavior of the SVM classifier when these hyperparameters take very small or very large values. Our results help in understanding the hyperparameter space that leads to an efficient heuristic method of searching for hyperparameter values with small generalization errors. The analysis also indicates that if complete model selection using the gaussian kernel has been conducted, there is no need to consider linear SVM.     

The influence of nonlinear fields on miniature hydrophone calibration using the planar scanning technique

Miniature polyvinylidene fluoride (PVDF) hydrophones used in determining the power and intensity output of ultrasonic fields, including those radiated from diagnostic ultrasound equipment, were calibrated under a variety of field conditions using the planar scanning technique. A diagnostic B-scan piston-type transducer was used as a source, and the output intensity (spatial-peak pulse-average, or SPPA) was varied from 2 to 30 W/cm(2) while the total power was kept constant. The higher-intensity waveforms were significantly nonlinear in the focal region of the source. When the lateral beam profiles of the source (as measured by the hydrophone to be calibrated) were determined by positive-peak-detecting the ultrasonic pulse, the calibrated pressure sensitivity of the hydrophone systematically decreased as the field became progressively more nonlinear. When the beam profiles were measured using the pulse intensity integral, no systematic dependence of the calibration on field linearity was noted. These results imply that measured values of power and intensity of ultrasound diagnostic equipment may be dependent on the methodology utilized to map the lateral beam profiles of the transducer being measured, and the extent of nonlinear effects in the field under characterization.     

Evaluation of physiological work demands and low back neuromuscular fatigue on nurses working in geriatric wards

This study evaluated the physiological demands and low back neuromuscular fatigue patterns following a daytime work shift of 21 female nurses working in geriatric wards. Subjects' heart rate (HR) at work was monitored for 8 h and surface electromyogram (EMG) of their back muscle was recorded during a 1-minute horizontal trunk holding test before and after work. Results showed that the nurses had heart rates exceeding 90 beats/min in 57% and 110 beats/min in 19% of their working hours. The EMG revealed a significant drop in initial median frequency (MF) (p = 0.04) and increase in negative slope of the MF/time plot (p<0.001) of the back muscle after work. These suggest that the muscles were fatigued after work. The nurses rated patient lifting, transfer and turning as most physically demanding, and these corresponded to the highest heart rates recorded. The physiological and neuromuscular strain on the nurses indicated that extreme care should be exercised at work, particularly towards the end of a work shift when the muscles have become fatigued.     

Issues in the development, dissemination, and effect of an evidence-based guideline for managing sore throat in adults

BACKGROUND: In October 1995 the University of Michigan Healthcare System initiated a program to develop and implement guidelines for primary care in an effort to improve the quality and cost-effectiveness of care for common conditions associated with wide variations in clinical practice. One of these conditions was Group A beta-hemolytic streptococcus (GABHS), present in 5% to 20% of adults complaining of sore throat. METHODS: A draft guideline was developed on the basis of a theoretical model of sore throat management, local data, and research evidence. The guideline was revised to reflect physicians' beliefs and practices regarding sore throat management. Guideline recommendations depended only on the number of clinical signs experienced by the patient and included testing only if it was likely to provide additional information about the probability of GABHS. Data on pre- and postdissemination data on patients presenting with sore throat were collected. RESULTS: When physicians believed testing or antibiotics were unnecessary, only 7% of patients demanded screening and only 6% of patients wanted antibiotics. Physician beliefs about a patient's need for testing agreed with guideline recommendations in 63% of patients both before and after guideline dissemination. DISCUSSION: Disseminating locally modified, evidence-based guidelines may not be sufficient to produce practice changes. If the guideline had been followed, the amount of testing would have been reduced by 17% and the appropriateness of testing improved for 32% of sore throat patients. The results indicate the need for implementation efforts that go beyond presenting evidence, even when that evidence is from both the literature and the local practice setting.