Prognostic and clinicopathological value of CDK12 mutation in prostate cancer: a meta-analysis.

BACKGROUND: Cyclin-dependent kinase 12 (CDK12) mutation has been shown to be associated with the prognosis and clinicopathological characteristics of various tumors. The aim of this meta-analysis was to investigate the role of mutations in prostate cancer (PCa). RESEARCH DESIGN AND METHODS: PubMed/Medline, EMBASE, Cochrane Library, and Web of Science database were searched for relevant articles. Meta-analysis was performed by using RevMan5.3 software, and the quality of the included literature was evaluated according to the Newcastle-Ottawa scale (NOS). RESULTS: A total of 13 studies comprising 5182 participants were enrolled in this meta-analysis. The frequency of CDK12 mutation in PCa was 7.26%. CDK12 mutation was significantly correlated with poor OS/PFS and had a shorter time to progress to CRPC. CDK12 mutant was associated with high-grade Gleason scores, while no relationships were found among CDK12 mutant, age, and the PSA level at diagnosis. CONCLUSION: This meta-analysis indicates that patients with CDK12 mutation have poor prognosis in PCa. CDK12 may be used as a biomarker for molecular subtype and a potential therapeutic target of PCa.

Probiotics and synbiotics show clinical efficacy in treating gestational diabetes mellitus: A meta-analysis.

BACKGROUND: This study performed a systematic and meta-analysis of randomized controlled trials (RCTs) to explore the efficacy of probiotic- and symbiotic-based supplements in the treatment of gestational diabetes mellitus (GDM). METHODS: We performed a meta-analysis to evaluate the efficacy of probiotics/synbiotics in GDM treatment, following a systematic search in Web of Science, PubMed, Cochrane Library, and EBSCO databases for articles published up to July 2020. RESULTS: In total, 12 RCTs comprising 894 participants, were analyzed. Compared to the placebo, patients administered with probiotic and synbiotic supplements benefited more with regards to glucose and lipid metabolism as well as anti-inflammation and antioxidant capacity including insulin of change (WMD: 3.57, 95%CI: -5.26, -1.88), very-low-density lipoprotein (VLDL) (WMD: -5.03, 95%CI: -8.26, -1.79), nitric oxide (NO) at the end of trial (WMD: 2.31, 95%CI: 0.91, 3.70), total antioxidant capacity (TAC) at the end of trial (SMD: 0.74, 95%CI: 0.21, 1.27), high-sensitivity C-reactive protein (hsCRP) at the end of trial (SMD: -1.23, 95%CI: -1.97, -0.49). Besides, probiotic and synbiotic supplements improved outcomes on fetal hyperbilirubinemia risk (RR: 0.26, 95%CI: 0.12, 0.55), fetal macrosomia risk (RR: 0.47, 95%CI: 0.27, 0.83) and newborn weight (SMD: -0.29, 95%CI: -0.50, -0.09). CONCLUSIONS: Findings from this work demonstrate that probiotic/symbiotic-based interventions improve glucose and lipid metabolism, anti-inflammatory and antioxidant ability in diet-controlled GDM patients, and exert beneficial outcomes on fetal hyperbilirubinemia, fetal macrosomia, and newborn weight.

Surface Charge Measurements with Scanning Ion Conductance Microscopy Provide Insights into Nitrous Acid Speciation at the Kaolin Mineral-Air Interface.

Unique surface properties of aluminosilicate clay minerals arise from anisotropic distribution of surface charge across their layered structures. Yet, a molecular-level understanding of clay mineral surfaces has been hampered by the lack of analytical techniques capable of measuring surface charges at the nanoscale. This is important for understanding the reactivity, colloidal stability, and ion-exchange capacity properties of clay minerals, which constitute a major fraction of global soils. In this work, scanning ion conductance microscopy (SICM) is used for the first time to visualize the surface charge and topography of dickite, a well-ordered member of the kaolin subgroup of clay minerals. Dickite displayed a pH-independent negative charge on basal surfaces whereas the positive charge on edges increased from pH 6 to 3. Surface charges responded to malonate addition, which promoted dissolution/precipitation reactions. Results from SICM were used to interpret heterogeneous reactivity studies showing that gas-phase nitrous acid (HONO) is released from the protonation of nitrite at Al-OH2+ groups on dickite edges at pH well above the aqueous pKa of HONO. This study provides nanoscale insights into mineral surface processes that affect environmental processes on the local and global scale.

Imaging effects of hyperosmolality on individual tricellular junctions.

The use of hyperosmolar agents (osmotherapy) has been a major treatment for intracranial hypertension, which occurs frequently in brain diseases or trauma. However, side-effects of osmotherapy on the brain, especially on the blood-brain barrier (BBB) are still not fully understood. Hyperosmolar conditions, termed hyperosmolality here, are known to transiently disrupt the tight junctions (TJs) at the endothelium of the BBB resulting in loss of BBB function. Present techniques for evaluation of BBB transport typically reveal aggregated responses from the entirety of BBB transport components, with little or no opportunity to evaluate heterogeneity present in the system. In this study, we utilized potentiometric-scanning ion conductance microscopy (P-SICM) to acquire nanometer-scale conductance maps of Madin-Darby Canine Kidney strain II (MDCKII) cells under hyperosmolality, from which two types of TJs, bicellular tight junctions (bTJs) and tricellular tight junctions (tTJs), can be visualized and differentiated. We discovered that hyperosmolality leads to increased conductance at tTJs without significant alteration in conductance at bTJs. To quantify this effect, an automated computer vision algorithm was designed to extract and calculate conductance components at both tTJs and bTJs. Additionally, lowering Ca2+ concentration in the bath facilitates tTJ disruption under hyperosmolality. Strengthening tTJ structure by overexpressing immunoglobulin-like domain-containing receptor 1 (ILDR1) protein abrogates the effect of hyperosmolality. We posit that osmotic stress physically disrupts tTJ structure, as evidenced by super-resolution microscopy. Findings from this study not only provide a high-resolution view of TJ structure and function, but also can inform current osmotherapy and drug delivery strategies for brain diseases.

Quantitative Visualization of Nanoscale Ion Transport.

Understanding ion transport properties at various interfaces, especially at small length scales, is critical in advancing our knowledge of membrane materials and cell biology. Recently, we described potentiometric-scanning ion conductance microscopy (P-SICM) for ion-conductance measurement in polymer membranes and epithelial cell monolayers at discrete points in a sample. Here, we combine hopping mode techniques with P-SICM to allow simultaneous nanometer-scale conductance and topography mapping. First validated with standard synthetic membranes and then demonstrated in living epithelial cell monolayers under physiological conditions, this new method allows direct visualization of heterogeneous ion transport of biological samples for the first time. These advances provide a noncontact local probe, require no labeling, and present a new tool for quantifying intrinsic transport properties of a variety of biological samples.

Membrane patches as ion channel probes for scanning ion conductance microscopy.

We describe dual-barrel ion channel probes (ICPs), which consist of an open barrel and a barrel with a membrane patch directly excised from a donor cell. When incorporated with scanning ion conductance microscopy (SICM), the open barrel (SICM barrel) serves to measure the distance-dependent ion current for non-invasive imaging and positioning of the probe in the same fashion of traditional SICM. The second barrel with the membrane patch supports ion channels of interest and was used to investigate ion channel activities. To demonstrate robust probe control with the dual-barrel ICP-SICM probe and verify that the two barrels are independently addressable, current-distance characteristics (approach curves) were obtained with the SICM barrel and simultaneous, current-time (I-T) traces were recorded with the ICP barrel. To study the influence that the distance between ligand-gated ion channels (i.e., large conductance Ca2+-activated K+ channels/BK channels) and the ligand source (i.e., Ca2+ source) has on channel activations, ion channel activities were recorded at two fixed probe-substrate distances (Dps) with the ICP barrel. The two fixed positions were determined from approach curves acquired with the SICM barrel. One position was defined as the "In-control" position, where the probe was in close proximity to the ligand source; the second position was defined as the "Far" position, where the probe was retracted far away from the ligand source. Our results confirm that channel activities increased dramatically with respect to both open channel probability and single channel current when the probe was near the ligand source, as opposed to when the probe was far away from the ligand source.

Capturing Rare Conductance in Epithelia with Potentiometric-Scanning Ion Conductance Microscopy.

Tight junctions (TJs) are barrier forming structures of epithelia and can be described as tightly sealed intercellular spaces. Transport properties have been extensively studied for bicellular TJs (bTJs). Knowledge of the barrier functions of tricellular junctions (tTJs) are less well understood, due largely to a lack of proper techniques to locally measure discrete tTJ properties within a much larger area of epithelium. In this study, we use a nanoscale pipet to precisely locate tTJs within epithelia and measure the apparent local conductance of tTJs with a technique termed potentiometric scanning ion conductance microscopy (P-SICM). P-SICM shows the ability to differentiate transport through tTJs and bTJs, which was not possible with previous techniques and assays. We describe P-SICM investigations of both wild type and tricellulin overexpression Madin-Darby Canine Kidney (strain II, MDCKII) cells.

Viral interactions with the blood-brain barrier: old dog, new tricks.

Brain endothelial cells form a unique cellular structure known as the tight junction to regulate the exchanges between the blood and the parenchyma by limiting the paracellular diffusion of blood-borne substance. Together with the restricted pathway of transcytosis, the tight junction in the brain endothelial cells provides the central nervous system (CNS) with effective protection against both the foreign pathogens and the host immune cells, which is also termed the "blood-brain barrier." The blood-brain barrier is particularly important for defending against neurotropic viral infections that have become a major source of diseases worldwide. Many neurotropic viruses are able to cross the BBB and infect the CNS through very poorly understood processes. This review focuses upon the structural and functional changes of the brain endothelial tight junction in response to viral infections in the CNS and how the tight junction changes may be studied with advanced imaging and recording approaches to reveal novel processes used by the viruses to cross the barrier system. Additional emphasis is placed upon new countermeasures that can act directly upon the tight junction to improve the pathogen clearance and minimize the inflammatory damage.

A proposed route to independent measurements of tight junction conductance at discrete cell junctions.

Direct recording of tight junction permeability is of pivotal importance to many biologic fields. Previous approaches bear an intrinsic disadvantage due to the difficulty of separating tight junction conductance from nearby membrane conductance. Here, we propose the design of Double whole-cell Voltage Clamp - Ion Conductance Microscopy (DVC-ICM) based on previously demonstrated potentiometric scanning of local conductive pathways. As proposed, DVC-ICM utilizes two coordinated whole-cell patch-clamps to neutralize the apical membrane current during potentiometric scanning, which in models described here will profoundly enhance the specificity of tight junction recording. Several potential pitfalls are considered, evaluated and addressed with alternative countermeasures.

Potentiometric-scanning ion conductance microscopy.

We detail the operation mechanism and instrumental limitations for potentiometric-scanning ion conductance microscopy (P-SICM). P-SICM makes use of a dual-barrel probe, where probe position is controlled by the current measured in one barrel and the potential is measured in a second barrel. Here we determine the interaction of these two barrels and resultant effects in quantitation of signals. Effects due to the size difference in pipet tip opening are examined and compared to model calculations. These results provide a basis for quantitation and image interpretation for P-SICM.

Free radical reactions in two dimensions: a case study on photochlorination of graphene.

Graphene, a two-dimensional giant-molecule of sp(2) -bonded carbon atoms, provides a perfect platform for studying free radical reaction chemistry in two-dimensions, which holds promise to control the chemical functionality of graphene. Free-radical photochlorination of graphene is used as an example to investigate the thickness, stacking order, and single- and double-side dependent reactivity in graphene. Anomalously low reactivity is observed in the photochlorination of AB-stacked bilayer graphene in comparison with that of few-layer graphene. Double-sided chlorination of graphene shows higher reactivity and chlorine coverage than single-sided reaction. It is also experimentally and theoretically demonstrated that chlorine free radicals at low coverage prefer to form a stable charge-transfer complex with graphene, which highly enhances graphene's conductivity and simultaneously generates a pseudo-bandgap through noninvasive doping. Moreover, the initial accumulation of chlorine radicals is considered as the rate-determining step of photochlorination of graphene.

Potentiometric-scanning ion conductance microscopy for measurement at tight junctions.

Scanning Ion Conductance Microscopy (SICM) has been developed originally for high-resolution imaging of topographic features. Recently, we have described a hybrid voltage scanning mode of SICM, termed Potentiometric-SICM (P-SICM) for recording transmembrane ionic conductance at specific nanostructures of synthetic and biological interfaces. With this technique, paracellular conductance through tight junctions - a subcellular structure that has been difficult to interrogate previously - has been realized. P-SICM utilizes a dual-barrel pipet to differentiate paracellular from transcellular transport processes with nanoscale spatial resolution. The unique combination of voltage scanning and topographic imaging enables P-SICM to capture paracellular conductance within a nominal radius of several hundred nanometers. This review summarizes recent advances in paracellular conductance recording with an emphasis on the P-SICM based approach, which is applied to detect claudin-2 mediated permeability changes at the tight junction.