Dual roles of the conditional extracellular vesicles derived from biofilms: Promoting and inhibiting bacterial biofilm growth.

Antibiotic-resistant biofilm infections have emerged as public health concerns because of their enhanced tolerance to high-dose antibiotic treatments. The biofilm life cycle involves multiple developmental stages, which are tightly regulated by active cell-cell communication via specific extracellular signal messengers such as extracellular vesicles. This study was aimed at exploring the roles of extracellular vesicles secreted by at different developmental stages in controlling biofilm growth.

Exosomes as Powerful Engines in Cancer: Isolation, Characterization and Detection Techniques.

Exosomes, powerful extracellular nanovesicles released from almost all types of living cells, are considered the communication engines (messengers) that control and reprogram physiological pathways inside target cells within a community or between different communities. The cell-like structure of these extracellular vesicles provides a protective environment for their proteins and DNA/RNA cargos, which serve as biomarkers for many malicious diseases, including infectious diseases and cancers. Cancer-derived exosomes control cancer metastasis, prognosis, and development.

Generation of a human induced pluripotent stem cell line PUMCi001-A from a patient with Krabbe disease.

We have generated PUMCi001-A, an induced pluripotent stem cells (iPSC) line from dermal fibroblasts of a 13-year-old male Krabbe disease patient with two hemizygous (461C > A and 1244G > A) mutations in Galactocerebrosidase (GALC) gene using a Sendai viral delivery of OCT4, SOX2, KLF4, and c-MYC. The PUMCi001-A iPSC line carried the GALC mutations, displayed typical iPSC morphology, expressed pluripotent stem cell makers, exhibited a normal karyotype and differentiation capacity into three germ layers.

Paper-based ITP technology: An application to specific cancer-derived exosome detection and analysis.

Exosomes derived from cancer cells/tissues have great potential for early cancer diagnostic use, but their clinical potential has not been fully explored because of a lack of cost-effective multiplex approaches capable of effectively isolating and identifying specific exosome populations and analyzing their content biomarkers. This study was aimed at overcoming the technical barrier by developing a paper-based isotachophoresis (ITP) technology capable of 1) rapid isolation and identification of exosomes from both malignant and healthy cells and 2) multiplex detection of selected exosomal protein biomarkers of the target exosomes. The technology integrates the focusing power of ITP and the multiplex capability of paper-based lateral flow to achieve on-board separation of target exosomes from large extracellular vesicles, followed by electrokinetic enrichment of the targets, leading to an ultrasensitive platform for comprehensive exosome analysis.

Bioinspired Peptoid Nanotubes for Targeted Tumor Cell Imaging and Chemo-Photodynamic Therapy.

Substantial progress has been made in applying nanotubes in biomedical applications such as bioimaging and drug delivery due to their unique architecture, characterized by very large internal surface areas and high aspect ratios. However, the biomedical applications of organic nanotubes, especially for those assembled from sequence-defined molecules, are very uncommon. In this paper, the synthesis of two new peptoid nanotubes (PepTs1 and PepTs2) is reported by using sequence-defined and ligand-tagged peptoids as building blocks.

Paper-based cascade cationic isotachophoresis: Multiplex detection of cardiac markers.

Paper-based analytical devices (PADs) are widely used in point-of-care testing (POCT) as they are cost-effective, simple and straightforward. However, poor sensitivity hinders their use in detecting diseases with low abundance biomarkers. The poor detection limit of PADs is mainly attributed to the low concentration of analytes, and the complexity of biological fluid, leading to insufficient interactions between analytes and capture antibodies.

Immunobinding-induced alteration in the electrophoretic mobility of proteins: An approach to studying the preconcentration of an acidic protein under cationic isotachophoresis.

The objective of this study is to explore an approach for analyzing negatively charged proteins using paper-based cationic ITP. The rationale of electrophoretic focusing the target protein with negative charges under unfavorable cationic ITP condition is to modify the electrophoretic mobility of the target protein through antigen-antibody immunobinding. Cationic ITP was performed on a paper-based analytical device that was fabricated using fiberglass paper.

Sarcomere length-dependent effects on Ca-troponin regulation in myocardium expressing compliant titin.

Cardiac performance is tightly regulated at the cardiomyocyte level by sarcomere length, such that increases in sarcomere length lead to sharply enhanced force generation at the same Ca concentration. Length-dependent activation of myofilaments involves dynamic and complex interactions between a multitude of thick- and thin-filament components. Among these components, troponin, myosin, and the giant protein titin are likely to be key players, but the mechanism by which these proteins are functionally linked has been elusive.

Effects of cardiomyopathy-linked mutations K15N and R21H in tropomyosin on thin-filament regulation and pointed-end dynamics.

Missense mutations K15N and R21H in striated muscle tropomyosin are linked to dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM), respectively. Tropomyosin, together with the troponin complex, regulates muscle contraction and, along with tropomodulin and leiomodin, controls the uniform thin-filament lengths crucial for normal sarcomere structure and function. We used Förster resonance energy transfer to study effects of the tropomyosin mutations on the structure and kinetics of the cardiac troponin core domain associated with the Ca-dependent regulation of cardiac thin filaments.

Role of the C-terminus mobile domain of cardiac troponin I in the regulation of thin filament activation in skinned papillary muscle strips.

The C-terminus mobile domain of cTnI (cTnI-MD) is a highly conserved region which stabilizes the actin-cTnI interaction during the diastole. Upon Ca-binding to cTnC, cTnI-MD participates in a regulatory switching that involves cTnI to switch from interacting with actin toward interacting with the Ca-regulatory domain of cTnC. Despite many studies targeting the cTnI-MD, the role of this region in the length-dependent activation of cardiac contractility is yet to be determined.

Functional significance of C-terminal mobile domain of cardiac troponin I.

Ca-regulation of cardiac contractility is mediated through the troponin complex, which comprises three subunits: cTnC, cTnI, and cTnT. As intracellular [Ca] increases, cTnI reduces its binding interactions with actin to primarily interact with cTnC, thereby enabling contraction. A portion of this regulatory switching involves the mobile domain of cTnI (cTnI-MD), the role of which in muscle contractility is still elusive.

Dynamic Equilibrium of Cardiac Troponin C's Hydrophobic Cleft and Its Modulation by Ca Sensitizers and a Ca Sensitivity Blunting Phosphomimic, cTnT(T204E).

Several studies have suggested that conformational dynamics are important in the regulation of thin filament activation in cardiac troponin C (cTnC); however, little direct evidence has been offered to support these claims. In this study, a dye homodimerization approach is developed and implemented that allows the determination of the dynamic equilibrium between open and closed conformations in cTnC's hydrophobic cleft. Modulation of this equilibrium by Ca, cardiac troponin I (cTnI), cardiac troponin T (cTnT), Ca-sensitizers, and a Ca-desensitizing phosphomimic of cTnT (cTnT(T204E) is characterized.

Recent progress in nanomaterials for gene delivery applications.

Nanotechnology-based gene delivery is the division of nanomedicine concerned with the synthesis, characterization, and functionalization of nanomaterials to be used in targeted-gene delivery applications. Nanomaterial-based gene delivery systems hold great promise for curing fatal inherited and acquired diseases, including neurological disorders, cancer, cardiovascular diseases, and acquired immunodeficiency syndrome (AIDS). However, their use in clinical applications is still controversial.

A specific nucleophilic ring-opening reaction of aziridines as a unique platform for the construction of hydrogen polysulfides sensors.

A hydrogen polysulfide mediated aziridine ring-opening reaction was discovered. Based on this reaction, a novel H2S(n)-specific chemosensor (AP) was developed. AP showed high sensitivity and selectivity for H2S(n).

Enhancing the output current of a CdTe solar cell via a CN-free hydrocarbon luminescent down-shifting fluorophore with intramolecular energy transfer and restricted internal rotation characteristics.

A CN-free hydrocarbon fluorophore (Perylene-TPE) was synthesized as a new luminescent down-shifting (LDS) material. Its photophysical properties in both the solution state and the solid state were studied. The unity fluorescence quantum yield of Perylene-TPE observed in its solid state is considered to be from the characteristics of intramolecular energy transfer (IET) and restricted internal rotation (RIR).

Rational design of tetraphenylethylene-based luminescent down-shifting molecules: photophysical studies and photovoltaic applications in a CdTe solar cell from small to large units.

A rational design strategy of novel fluorophores for luminescent down-shifting (LDS) application was proposed and tested in this paper. Three new fluorophores (1a-c) with specific intramolecular charge transfer (ICT) and aggregation-induced emission (AIE) characteristics were synthesized as LDS molecules for increasing the output short circuit current density (Jsc) of a CdTe solar cell. Photophysical studies of their solution and solid states, and photovoltaic measurements of their PMMA solid films applied on a CdTe solar cell suggested that the specific spectroscopic properties and Jsc enhancement effects of these molecules were highly related to their chemical structures.

Cationic isotachophoresis separation of the biomarker cardiac troponin I from a high-abundance contaminant, serum albumin.

Cationic ITP was used to separate and concentrate fluorescently tagged cardiac troponin I (cTnI) from two proteins with similar isoelectric properties in a PMMA straight-channel microfluidic chip. In an initial set of experiments, cTnI was effectively separated from R-Phycoerythrin using cationic ITP in a pH 8 buffer system. Then, a second set of experiments was conducted in which cTnI was separated from a serum contaminant, albumin.

FRET study of the structural and kinetic effects of PKC phosphomimetic cardiac troponin T mutants on thin filament regulation.

FRET was used to investigate the structural and kinetic effects that PKC phosphorylations exert on Ca(2+) and myosin subfragment-1 dependent conformational transitions of the cardiac thin filament. PKC phosphorylations of cTnT were mimicked by glutamate substitution. Ca(2+) and S1-induced distance changes between the central linker of cTnC and the switch region of cTnI (cTnI-Sr) were monitored in reconstituted thin filaments using steady state and time resolved FRET, while kinetics of structural transitions were determined using stopped flow.

Molecular dynamics simulations of the cardiac troponin complex performed with FRET distances as restraints.

Cardiac troponin (cTn) is the Ca(2+)-sensitive molecular switch that controls cardiac muscle activation and relaxation. However, the molecular detail of the switching mechanism and how the Ca(2+) signal received at cardiac troponin C (cTnC) is communicated to cardiac troponin I (cTnI) are still elusive. To unravel the structural details of troponin switching, we performed ensemble Förster resonance energy transfer (FRET) measurements and molecular dynamic (MD) simulations of the cardiac troponin core domain complex.

Structural basis for the in situ Ca(2+) sensitization of cardiac troponin C by positive feedback from force-generating myosin cross-bridges.

The in situ structural coupling between the cardiac troponin (cTn) Ca(2+)-sensitive regulatory switch (CRS) and strong myosin cross-bridges was investigated using Förster resonance energy transfer (FRET). The double cysteine mutant cTnC(T13C/N51C) was fluorescently labeled with the FRET pair 5-(iodoacetamidoethyl)aminonaphthelene-1-sulfonic acid (IAEDENS) and N-(4-dimethylamino-3,5-dinitrophenyl)maleimide (DDPM) and then incorporated into detergent skinned left ventricular papillary fiber bundles. Ca(2+) titrations of cTnC(T13C/N51C)AEDENS/DDPM-reconstituted fibers showed that the Ca(2+)-dependence of the opening of the N-domain of cTnC (N-cTnC) statistically matched the force-Ca(2+) relationship.

Structural and kinetic effects of hypertrophic cardiomyopathy related mutations R146G/Q and R163W on the regulatory switching activity of rat cardiac troponin I.

Mutations in cardiac troponin I (cTnI) that cause hypertrophic cardiomyopathy (HCM) have been reported to change the contractility of cardiac myofilaments, but the underlying molecular mechanism remains elusive. In this study, Förster resonance energy transfer (FRET) was used to investigate the specific structural and kinetic effects that HCM related rat cTnI mutations R146G/Q and R163W exert on Ca(2+) and myosin S1 dependent conformational transitions in rat cTn structure. Ca(2+)-induced changes in interactions between cTnC and cTnI were individually monitored in reconstituted thin filaments using steady state and time resolved FRET, and kinetics were determined using stopped flow.

Disease-causing R1185C mutation of WNK4 disrupts a regulatory mechanism involving calmodulin binding and SGK1 phosphorylation sites.

The R1185C mutation in WNK4 is associated with pseudohypoaldosteronism type II (PHAII). Unlike other PHAII-causing mutations in the acidic motif, the R1185C mutation is located in the COOH-terminal region of WNK4. The goal of the study is to determine what properties of WNK4 are disrupted by the R1185C mutation.

Enzymatic amplification of DNA/RNA hybrid molecular beacon signaling in nucleic acid detection.

A rapid assay operable under isothermal or nonisothermal conditions is described, where the sensitivity of a typical molecular beacon (MB) system is improved by using thermostable RNase H to enzymatically cleave an MB composed of a DNA stem and an RNA loop (R/D-MB). On hybridization of the R/D-MB to target DNA, there was a modest increase in fluorescence intensity (~5.7× above background) due to an opening of the probe and a concomitant reduction in the Förster resonance energy transfer efficiency.

Endoplasmic reticulum stress is involved in podocyte apoptosis induced by saturated fatty acid palmitate.

Background: Podocyte apoptosis is recently indicated as an early phenomenon of diabetic nephropathy. Pancreatic β-cells exposed to saturated free fatty acid palmitate undergo irreversible endoplasmic reticulum (ER) stress and consequent apoptosis, contributing to the onset of diabetes. We hypothesized that palmitate could induce podocyte apoptosis via ER stress, which initiates or aggravates proteinuria in diabetic nephropathy.