Human mesenchymal stem cells at the single-cell level: simultaneous seven-colour immunofluorescence

Extracellular, intracellular or surface proteins can be used as putative markers to characterize human mesenchymal stem cells (hMSC). However, these markers are also expressed by other cell types and primary cell pools reveal considerable heterogeneity. Therefore, the simultaneous detection of several markers on a single cell appears to be an attractive approach to identify hMSC. Here we demonstrate the specific distinction of human MSC from human osteoblasts via seven-colour fluorescence on the single cell level with simultaneous marker detection of CD44, CD105/endoglin, CD106/VCAM-1, collagen-IV, fibronectin, actin and DAPI nuclear staining. We performed spectral image acquisition using a Sagnac-type interferometer. Subsequent linear unmixing allowed for decomposition of each pixel in its spectral components. Our approach reveals a typical expression profile of the adherent singular cells, allowing the specific distinction between hMSC and osteoblasts on the single cell level.     

Determining a continuous marker for sleep depth

Detection and quantification of sleep arousals is an important issue, as the frequent arousals are known to reduce the quality of sleep and cause daytime sleepiness. In typical sleep staging, electroencephalograph (EEG) is the core signal and based on the visual inspection of the frequency content of EEG, non-rapid eye movement sleep is staged into four somewhat rough categories. In this study, we aimed at developing a continuous marker based on a more rigorous spectral analysis of EEG to measure or quantify the depth of sleep. In order to develop such a marker, we obtained the time-frequency map of two EEG channels around sleep arousals and identified the frequency bands that show the most change during arousals. We then evaluated classification performance of the potential signals for representing the depth of sleep, using receiver operating characteristic analysis. Our comparisons based on the area under the curve values revealed that the sum of absolute powers in alpha and beta bands is a good continuous marker to represent the depth of sleep. Higher values of this marker indicate low-quality sleep and vice versa. We believe that use of this marker will lead to a better quantification of sleep quality.     

A novel method for analysis of single ion channel signal based on wavelet transform

A single ion channel signal was analysed by the power distribution fraction constructed by a discrete wavelet transform. Average opening time and energy distribution of the signal can be obtained directly by this method. The method can also be used when the signal is corrupted by noise. By contrast, the conventional frequency domain analysis method--power spectral density--is less effective. Power distribution fraction will therefore give more useful information in analysis of experimental ion channel signals, principally by giving values of the mean channel opening time. The method may be applied to distinguish different ion channels more efficiently and to find their reactions to drugs.     

Representation and classification of breath sounds recorded in an intensive care setting using neural networks

Objective.Develop and test methods for representing and classifying breath sounds in an intensive care setting. Methods.Breath sounds were recorded over the bronchial regions of the chest. The breath sounds were represented by their averaged power spectral density, summed into feature vectors across the frequency spectrum from 0 to 800 Hertz. The sounds were segmented by individual breath and each breath was divided into inspiratory and expiratory segments. Sounds were classified as normal or abnormal. Different back-propagation neural network configurations were evaluated. The number of input features, hidden units, and hidden layers were varied.Results.2127 individual breath sounds from the ICU patients and 321breaths from training tapes were obtained. Best overall classification rate for the ICU breath sounds was 73% with 62% sensitivity and 85% specificity. Best overall classification rate for the training tapes was 91% with 87%sensitivity and 95% specificity. Conclusions.Long term monitoring of lung sounds is not feasible unless several barriers can be overcome. Several choices in signal representation and neural network design greatly improved the classification rates of breath sounds. The analysis of transmitted sounds from the trachea to the lung is suggested as an area for future study. This revised version was published online in July 2006 with corrections to the Cover Date.     

Laboratory Exercises to Teach Clinically Relevant Chemistry of Antibiotics

Objectives. To design, implement, and evaluate student performance on clinically relevant chemical and spectral laboratory exercises on antibiotics.Design. In the first of 2 exercises, second-year pharmacy students enrolled in an integrated laboratory sequence course studied the aqueous stability of ß-lactam antibiotics using a spectral visual approach. In a second exercise, students studied the tendency of tetracycline, rifamycins, and fluoroquinolones to form insoluble chelate complexes (turbidity) with polyvalent metals.Assessment. On a survey to assess achievement of class learning objectives, students agreed the laboratory activities helped them better retain important information concerning antibiotic stability and interactions. A significant improvement was observed in performance on examination questions related to the laboratory topics for 2012 and 2013 students compared to 2011 students who did not complete the laboratory. A 1-year follow-up examination question administered in a separate course showed >75% of the students were able to identify rifamycins-food interactions compared with <25% of students who had not completed the laboratory exercises.Conclusion. The use of spectral visual approaches allowed students to investigate antibiotic stability and interactions, thus reinforcing the clinical relevance of medicinal chemistry. Students’ performance on questions at the 1-year follow-up suggested increased retention of the concepts learned as a result of completing the exercises.     

Assessment of Technological Capabilities for Forming Al-C-B System Coatings on Steel Surfaces by Electrospark Alloying Method

In this paper, the possibility of applying the electrospark alloying (ESA) method to obtain boron-containing coatings characterised by increased hardness and wear resistance is considered. A new method for producing such coatings is proposed. The method consists in applying grease containing aluminium powder and amorphous boron to the surface to be treated and subsequently processing the obtained surface using the ESA method by a graphite electrode. The microstructural analysis of the Al-C-B coatings on steel C40 showed that the surface layer consists of several zones, the number and parameters of which are determined by the energy conditions of the ESA process. Durametric studies showed that with an increase in the discharge energy influence, the microhardness values of both the upper strengthened layer and the diffusion zone increased to W_p = 0.13 J, Hµ = 6487 MPa, and W_p = 4.9 J, Hµ = 12350 MPa, respectively. The results of X-ray diffraction analysis indicate that at the discharge energies of 0.13 and 0.55 J, the phase composition of the coating is represented by solid solutions of body-centred cubic lattice (BCC) and face-centred cubic lattice (FCC). The coatings obtained at W_p = 4.9 J were characterised by the presence of intermetallics Fe₄Al₁₃ and borocementite Fe₃ (CB) in addition to the solid solutions. The X-ray spectral analysis of the obtained coatings indicated that during the electrospark alloying process, the surface layers were saturated with aluminium, boron, and carbon. With increasing discharge energy, the diffusion zone increases; during the ESA process with the use of the discharge energy of 0.13 J for steel C40, the diffusion zone is 10–15 μm. When replacing a substrate made of steel C40 with the same one material but of steel C22, an increase in the thickness of the surface layer accompanied by a slight decrease in microhardness is observed as a result of processing with the use of the ESA method. There were simulated phase portraits of the Al-C-B coatings. It is shown that near the stationary points in the phase portraits, one can see either a slowing down of the evolution or a spiral twisting of the diffusion-process particle.     

一站式CT能谱灌注成像预测兔腋窝淋巴结性质

目的 探讨一站式CT能谱灌注成像定量参数预测兔腋窝淋巴结性质的应用价值。方法 将60只新西兰纯种雌性大白兔随机分为2组,分别建立兔乳腺癌腋窝转移性淋巴结（转移组）与炎性淋巴结动物模型（炎症组）。于建模后第4周末对实验兔行一站式CT能谱灌注成像扫描,扫描完成后摘取腋窝淋巴结行病理检查,并与CT图像逐一对照。采用两独立样本t检验比较2组能谱参数和灌注参数的差异,以Logistic回归和ROC曲线分析单一参数和联合参数诊断实验兔腋窝淋巴结性质的效能。结果 转移组淋巴结的血流量（BF）、血容量（BV）、动静脉期碘浓度（IC）、标准化碘基值（NIC）和40~70 keV间的能谱曲线斜率（λ）均高于炎症组（P均<0.05）,平均通过时间（MTT）和表面通透性（PS）差异无统计学意义（P均>0.05）。最佳联合参数（BF+动脉期λ+静脉期λ）的AUC为0.942,以0.65为临界值,其诊断实验兔腋窝乳腺癌转移性淋巴结的敏感度、特异度、阳性预测值和阴性预测值分别为79.68%、95.92%、92.91%和82.70%。结论 一站式CT能谱灌注成像定量参数鉴别兔腋窝乳腺癌转移性淋巴结与炎性淋巴结的诊断效能较好,联合参数（BF+动脉期λ+静脉期λ）具有较高诊断价值。