Image-based discrimination of the early stages of mesenchymal stem cell differentiation.

Mesenchymal stem cells (MSCs) are self-renewing, multipotent cells, which can be used in cellular and tissue therapeutics. MSCs cell number can be expanded in vitro, but premature differentiation results in reduced cell number and compromised therapeutic efficacies. Current techniques fail to discriminate the "stem-like" population from early stages (12 h) of differentiated MSC population. Here, we imaged nuclear structure and actin architecture using immunofluorescence and used deep learning-based computer vision technology to discriminate the early stages (6-12 h) of MSC differentiation. Convolutional neural network models trained by nucleus and actin images have high accuracy in reporting MSC differentiation; nuclear images alone can identify early stages of differentiation. Concurrently, we show that chromatin fluidity and heterochromatin levels or localization change during early MSC differentiation. This study quantifies changes in cell architecture during early MSC differentiation and describes a novel image-based diagnostic tool that could be widely used in MSC culture, expansion and utilization.

[Construction and application of natural stable isotope correction matrix in 13C-labeled metabolic flux analysis].

Stable isotope 13C labeling is an important tool to analyze cellular metabolic flux. The 13C distribution in intracellular metabolites can be detected via mass spectrometry and used as a constraint in intracellular metabolic flux calculations. Then, metabolic flux analysis algorithms can be employed to obtain the flux distribution in the corresponding metabolic reaction network. However, in addition to carbon, other elements such as oxygen in the nature also have natural stable isotopes (e.g., 17O, 18O). This makes the isotopic information of elements other than the 13C marker interspersed in the isotopic distribution measured by the mass spectrometry, especially that of the molecules containing many other elements, which leads to large errors. Therefore, it is essential to correct the mass spectrometry data before performing metabolic flux calculations. In this paper, we proposed a method for construction of correction matrix based on Python language for correcting the measurement errors due to natural isotope distribution. The method employed a basic power method for constructing the correction matrix with simple structure and easy coding implementation, which can be directly applied to data pre-processing in 13C metabolic flux analysis. The correction method was then applied to the intracellular metabolic flux analysis of 13C-labeled Aspergillus niger. The results showed that the proposed method was accurate and effective, which can serve as a reliable data correction method for accurate microbial intracellular metabolic flux analysis.

Piperazine Derivatives Enhance Epithelial Cell Monolayer Permeability by Increased Cell Force Generation and Loss of Cadherin Structures.

A major obstacle for topical and enteral drug delivery is the poor transport of macromolecular drugs through the epithelium. One potential solution is the use of permeation enhancers that alter epithelial structures. Piperazine derivatives are known permeation enhancers that modulate epithelial structures, reduce transepithelial electrical resistance, and augment the absorption of macromolecular drugs. The mechanism by which piperazine derivatives disrupt the structures of epithelial monolayers is not well understood. Here, the effects of 1-phenylpiperazine and 1-methyl-4-phenylpiperazine are modeled in the epithelial cell line NRK-52E. Live-cell imaging reveals a dose-dependent gross reorganization of monolayers at high concentrations, but reorganization differs based on the piperazine molecule. Results show that low concentrations of piperazine derivatives increase myosin force generation within the cells and do not disrupt the cytoskeletal structure. Also, cytoskeletally attached cadherin junctions are disrupted before tight junctions. In summary, piperazines appear to increase myosin-mediated contraction followed by disruption of cell-cell contacts. These results provide new mechanistic insight into how transient epithelial permeation enhancers act and will inform of the development of future generations of transepithelial delivery systems.

Theoretical studies on identity S(N)2 reactions of lithium halide and methyl halide: a microhydration model.

Reactions of lithium halide (LiX, X = F, Cl, Br and I) and methyl halide (CH3X, X = F, Cl, Br and I) have been investigated at the B3LYP/6-31G(d) level of theory using the microhydration model. Beginning with hydrated lithium ion, four or two water molecules have been conveniently introduced to these aqueous-phase halogen-exchange S(N)2 reactions. These water molecules coordinated with the center metal lithium ion, and also interacted with entering and leaving halogen anion via hydrogen bond in complexes and transition state, which to some extent compensated hydration of halogen anion. At 298 K the reaction profiles all involve central barriers ΔE ( cent ) which are found to decrease in the order F > Cl > Br > I. The same trend is also found for the overall barriers (ΔE(ovr)) of the title reaction. In the S(N)2 reaction of sodium iodide and methyl iodide, the activation energy agrees well with the aqueous conductometric investigation.

Ultrasonic study of the charge mismatch effect in charge-ordered (Nd(0.75)Na(0.25))(x)(Nd(0.5)Ca(0.5))(1-x)MnO(3).

The resistivity, magnetization and ultrasonic properties of charge-ordered polycrystalline (Nd(0.75)Na(0.25))(x)(Nd(0.5)Ca(0.5))(1-x)MnO(3) have been investigated from 50 to 300 K. A considerable velocity softening accompanied by an attenuation peak was observed around the charge-ordering transition temperature (T(CO)) upon cooling. The simultaneous occurrence of the charge ordering (CO) and the ultrasonic anomaly implies strong electron-phonon coupling, which originates from the cooperative Jahn-Teller effect. At very low temperature, another broad attenuation peak was observed, which is attributed to the phase separation (PS) and gives a direct evidence of spin-phonon coupling in the compound. With increasing x, T(CO) shifts to lower temperature, the magnetization of the system is strengthened and the PS is enhanced. The temperature dependence of the longitudinal modulus shows that the Jahn-Teller coupling energy E(JT) decreases with increasing Na content. The analysis suggests that the charge mismatch effect may be the main reason for the suppression of the CO and enhancement of the PS.