MV-mimicking micelles loaded with PEG-serine-ACP nanoparticles to achieve biomimetic intra/extra fibrillar mineralization of collagen in vitro

Since their discovery, matrix vesicles (MVs) containing minerals have received considerable attention for their role in the mineralization of bone, dentin and calcified cartilage. Additionally, MVs' association with collagen fibrils, which serve as the scaffold for calcification in the organic matrix, has been repeatedly highlighted. The primary purpose of the present study was to establish a MVs–mimicking model (PEG-S-ACP/micelle) in vitro for studying the exact mechanism of MVs-mediated extra/intra fibrillar mineralization of collagen in vivo. In this study, high-concentration serine was used to stabilize the amorphous calcium phosphate (S-ACP), which was subsequently mixed with polyethylene glycol (PEG) to form PEG-S-ACP nanoparticles. The nanoparticles were loaded in the polysorbate 80 micelle through a micelle self-assembly process in an aqueous environment. This MVs–mimicking model is referred to as the PEG-S-ACP/micelle model. By adjusting the pH and surface tension of the PEG-S-ACP/micelle, two forms of minerals (crystalline mineral nodules and ACP nanoparticles) were released to achieve the extrafibrillar and intrafibrillar mineralization, respectively. This in vitro mineralization process reproduced the mineral nodules mediating in vivo extrafibrillar mineralization and provided key insights into a possible mechanism of biomineralization by which in vivo intrafibrillar mineralization could be induced by ACP nanoparticles released from MVs. Also, the PEG-S-ACP/micelle model provides a promising methodology to prepare mineralized collagen scaffolds for repairing bone defects in bone tissue engineering.     

Infrared spectroscopy of proteins

This review discusses the application of infrared spectroscopy to the study of proteins. The focus is on the mid-infrared spectral region and the study of protein reactions by reaction-induced infrared difference spectroscopy.     

生物组织散射元平均间距估计的一种新方法

生物组织散射元平均间中划描述生物组织微观结构特性和生物组织超微散射特性的重要参数。本文在对生物组织超声背向散射随机模的基础上,提出了基于生物组织超声背向散射信号突变点检测的工用射元平均间距估计的新方法。该方法是生物组织超声散射分析的有效方法。     

Myosin light chain kinase binding to plastic

Methionine-81 and/or -8 of the transmembrane sialoglycoprotein, glycophorin A, have been specifically alkylated with ¹³CH₃I to produce the sulfonium ion derivatives [S-[¹³C]methylmethionine-8]glycophorin A and [S-[¹³C]methylmethionine-8 and -81]glycophorin A. ¹³C NMR spectra of these species show that the resonances of the methyl groups of the modified glycophorins occur at 26.1 ppm downfield from Me₄Si. A spin-lattice relaxation time of 0.4 was observed for the ¹³C-enriched methyl resonances of the sulfonium ion derivatives of Met-8 and -81, which corresponds to an effective correlation time of < 2× 10^?10 s. Demethylation of the 2 glycophorin A sulfonium ion species with 2-mercaptoethanol produces native glycophorin A which now has the ε-carbon of the methionine residue(s) 45% isotopically enriched. The ε-carbon of Met-8 was found to occur at 15.7 ppm downfield from Me₄Si whereas the ε-carbon of Met-81 exhibited an unusual chemical shift of 2.0 ppm downfield from Me₄Si. The spin-lattice relaxation time of both resonances was found to be ～0.3 s.     

Multiple mechanisms of cytochrome P450-catalyzed substrate hydroxylations

We have examined the 5-$\text{exo}$-hydroxylation of camphor by cytochrome P450 in [¹⁸O] water/buffer solution. In the $\text{NADH}\text{O}{}_2\text{-dependent}$ reaction of the reconstituted multienzyme system, no ¹⁸O-label is observed in the product alcohol. Similarly, in the m-chloroperbenzoic acid or cumene hydroperoxide supported reactions with ferric P450, solvent oxygen is not incorporated into hydroxycamphor. When the analagous reaction is carried out using iodosobenzene as the exogenous oxidant, however, the alcoholic oxygen of the product is derived entirely from the solvent. These results cannot be explained by equilibration of the iodosobenzene oxygen with solvent water before reacting with P450, and suggest a unique mechanism for iodosobenzene-supported P450 oxygenations. We propose two distinct mechanistic activities for cytochrome P450: a hydroxylase, and an oxene transferase, with the former encompassing the classic oxygenase as well as “peroxygenase” reactions.     

Synthesis and relative stereochemistry of the four mercapturic acids derived from styrene oxide and N-acetylcysteine

The chemical reaction between (±)-styrene oxide and N-acetylcysteine produces both positional isomers ($\text{1}$ and $\text{2}$) as a mixture of diastereoisomers with a preference for the benzylic thioether isomer $\text{1}$ (2 : 1). Synthesis of the mercapturic acid conjugates from either (+)- or (?)-styrene oxide produces only two of the four possible stereoisomers. The single diastereoisomers of $\text{1}$ and $\text{2}$ were separated by high pressure liquid chromatography (HPLC) and identified by ¹H- and ¹³C-nuclear magnetic resonance (NMR). The relative stereochemistry at the benzylic carbon center of the mercapturic acid conjugates was assigned on the basis of the established chemical correlation between optically pure styrene oxide and its precursor mandelic acid, and considerations on the mechanism of ring opening of epoxides by sulfur nucleophiles. The stereochemical definition of the isomers $\text{3}$–$\text{6}$ should prove useful in investigations of the biotransformation of the glutathione (GSH) conjugates of styrene oxide.     

Myocardial Infarction Detection and Localization Using Optimal Features Based Lead Specific Approach

ObjectivesObjective of this paper is to present a reliable and accurate technique for Myocardial Infarction (MI) detection and localization.Material and methodsStationary wavelet transform has been used to decompose the ECG signal. Energy, entropy and slope based features were extracted at specific wavelet bands from selected lead of ECG. k-Nearest Neighbors (kNN) with Mahalanobis distance function has been used for classification. Sensitivity (Se), specificity (Sp), positive predictivity (+P), accuracy (Acc), and area under the receiver operating characteristics curve (AUC) analyzed over 200 subjects (52 health control, 148 with MI) from Physikalisch-Technische Bundesanstalt (PTB) database has been used for performance analysis. To handle the imbalanced data adaptive synthetic (ADASYN) sampling approach has been adopted.ResultsFor detection of MI, the proposed technique has shown an AUC = 0.99, Se = 98.62%, Sp = 99.40%, PPR = 99.41% and Acc = 99.00% using 12 top ranked features, extracted from multiple leads of ECG and AUC = 0.99, Se = 98.34%, Sp = 99.77%, PPR = 99.77% and Acc = 99.05% using 12 features extracted from a single ECG lead (i.e. lead V5). For localization of MI, the proposed technique has an AUC = 0.99, Se = 98.78%, Sp = 99.86%, PPR = 98.80%, and Acc = 99.76% using 5 top ranked features from multiple leads of ECG and AUC = 0.98, Se = 96.47%, Sp = 99.60%, PPR = 96.49% and Acc = 99.28% using 8 features extracted from a single ECG lead (i.e. lead V3).ConclusionThus for MI detection and localization, the proposed technique is independent of time-domain ECG fiducial markers and can work using specific leads of ECG.     

Flexible Analytic Wavelet Transform Based Features for Physical Action Identification Using sEMG Signals

ObjectivesElectromyography (EMG) is recording of the electrical activity produced by skeletal muscles. The classification of the EMG signals for different physical actions can be useful in restoring some or all of the lost motor functionalities in these individuals. Accuracy in classifying the EMG signal indicates efficient control of prosthesis.Material and methodsThe flexible analytic wavelet transform (FAWT) is used for classification of surface electromyography (sEMG) signals for identification of physical actions. FAWT is an efficient method for decomposition of sEMG signal into eight sub-bands, features namely neg-entropy, mean absolute value (MAV), variance (VAR), modified mean absolute value type 1 (MAV1), waveform length (WL), simple square integral (SSI), Tsallis entropy, integrated EMG (IEMG) are extracted from the sub-bands. Extracted features are fed into an extreme learning machine (ELM) classifier with sigmoid activation function.ResultsComprehensive experiments are conducted on the input sEMG signals and the accuracy, sensitivity and specificity scores are used for performance measurement. Experiments showed that among all sub-bands, the seventh sub-band provided the best performance where the recorded accuracy, sensitivity and specificity values were 99.36%, 99.36% and 99.93%, respectively. The comparison results showed best efficiency of proposed method as compared to other methods on the same dataset.ConclusionThis paper investigates the usage of the FAWT and ELM on sEMG signal classification. The results show that the proposed method is quite efficient in classification of the sEMG signals. It is also observed that the seventh sub-band of the FAWT provides the best discrimination property. In the future works, recent wavelet transform methods will be used for improving the classification performance.     

ROI-Based Compression Strategy of 3D MRI Brain Datasets for Wireless Communications

ObjectivesBecause of the large amount of medical imaging data, the transmission process becomes complicated in telemedicine applications. Thus, in order to adapt the data bit streams to the constraints related to the limitation of the bandwidths a reduction of the size of the data by compression of the images is essential. Despite the improvements in the field of compression, the transmission itself can also introduce errors. For this reason, it is important to develop an adequate strategy which will help reduce this volume of data without having to introduce some distortion and resist the errors introduced by the channel noise during transmission. Thus, in this paper, we propose a ROI-based coding strategy and unequal bit stream protection to meet this dual constraint.Material and methodsThe proposed ROI-based compression strategy with unequal bit stream protection is composed of three parts: the first one allows the extraction of the ROI region, the second one consists of a ROI-based coding and the third one allows an unequal protection of the ROI bit stream.First, the Regions Of Interest (ROI) are extracted by hierarchical segmentation of these regions according to a segmentation method based on the technique of Marker-based-watershed combined with the technique of active contours by level set. The resulting regions are selectively encoded by a 3D coder based on a shape adaptive discrete wavelet transform 3D-BISK, where the compression ratio of each region depends on its relevance in diagnosis. These obtained regions of interest are protected with an error-correcting code of Reed-Solomon type with a code rate that varies according to the relevance of the region by an unequal protection strategy (UEP).ResultsThe performance of the proposed compression scheme is evaluated in several ways. First, tests are performed to study the impact of errors on the different bit streams. In the first place, these tests are carried out in order to study the effect of the variation of the compression rates on the different bit streams. Secondly, different Reed Solomon error-correcting codes of different code rates are tested at different compression rates on a BSC channel. Finally, the performances of this coding strategy are compared with those of SPIHT 3D in the case of transmission on a BSC channel.ConclusionThe obtained results show that the proposed method is quite efficient in transmission time reduction. Therefore, our proposed scheme will reduce the volume of data without having to introduce some distortion and resist the errors introduced by the channel noise in the case of telemedicine.