Development of Magnetic Torque Stimulation (MTS) Utilizing Rotating Uniform Magnetic Field for Mechanical Activation of Cardiac Cells.

Regulation of cell signaling through physical stimulation is an emerging topic in biomedicine. BACKGROUND: While recent advances in biophysical technologies show capabilities for spatiotemporal stimulation, interfacing those tools with biological systems for intact signal transfer and noncontact stimulation remains challenging. Here, we describe the use of a magnetic torque stimulation (MTS) system combined with engineered magnetic particles to apply forces on the surface of individual cells. MTS utilizes an externally rotating magnetic field to induce a spin on magnetic particles and generate torsional force to stimulate mechanotransduction pathways in two types of human heart cells-cardiomyocytes and cardiac fibroblasts. METHODS: The MTS system operates in a noncontact mode with two magnets separated (60 mm) from each other and generates a torque of up to 15 pN µm across the entire area of a 35-mm cell culture dish. The MTS system can mechanically stimulate both types of human heart cells, inducing maturation and hypertrophy. RESULTS: Our findings show that application of the MTS system under hypoxic conditions induces not only nuclear localization of mechanoresponsive YAP proteins in human heart cells but also overexpression of hypertrophy markers, including ß-myosin heavy chain (ßMHC), cardiotrophin-1 (CT-1), microRNA-21 (miR-21), and transforming growth factor beta-1 (TGFß-1). CONCLUSIONS: These results have important implications for the applicability of the MTS system to diverse in vitro studies that require remote and noninvasive mechanical regulation.

Predictive factors for bacteremia in febrile infants with urinary tract infection.

This study aimed to investigate the predictive factors of concomitant bacteremia occurring in febrile infants who initially presented with pyuria and fever, and were subsequently diagnosed with culture-proven urinary tract infection (UTI). We conducted a retrospective cohort study for January 2010-October 2018 that included infants younger than six months with febrile UTI at a tertiary hospital. The study included 463 patients, of whom 34 had a concomitant bacteremic UTI. Compared to those in the non-bacteremic urinary tract infection (UTI) group, the bacteremic UTI group had a lower mean age; higher levels of C-reactive protein (CRP), delta neutrophil index (DNI, reflects the fraction of immature granulocytes) and blood urea nitrogen (BUN); lower levels of hemoglobin (Hb) and albumin; and a lower platelet count. Vesicoureteral reflux (VUR) was detected nearly twice as often in patients with bacteremic UTI compared to those with non-bacteremic UTI (59.3% vs. 30.6%; P = 0.003). Univariate logistic analyses showed that age ≤90 days; higher DNI, CRP, and creatinine levels; lower Hb and albumin levels; and the presence of VUR were predictors for bacteremic UTI. On multivariate logistic regression analysis, age ≤90 days, higher DNI and CRP levels, and the presence of VUR were independent predictors of bacteremic UTI. The area under the receiver operating characteristic curve of the multivariate model was 0.859 (95% CI, 0.779-0.939; P < 0.001). Age ≤90 days, higher DNI and CRP values may help predict bacteremia of febrile infants younger than 6 months with UTI. Vesicoureteral reflux imaging is also recommended in infants with bacteremic UTI to evaluate VUR.

A systematic approach to enhance off-axis directional electromagnetic wave by two-dimensional structure design.

In this study, we propose a two-dimensional (2D) dielectric structure tailored by a systematic design approach on the exit side of a metallic aperture to enhance the off-axis electromagnetic (EM) wave. We adopted a phase field method based topology optimization scheme and designed an arbitrary 2D dielectric structure in order to steer outward beaming through an aperture to a specific direction. Beyond previous one-dimensional structure, we proposed an arbitrary 2D dielectric structure through the introduced design process defining not only x- but also y-directional dielectric structural boundaries simultaneously and experimentally confirmed enhanced EM wave transmission to a desired direction.

Inverse design of the absorbing layer for detection enhancement in near-infrared range.

In spite of rapidly increasing demand and various applications of infrared (IR) detectors, their design process for the performance improvement has been mostly dependent on researchers' intuition and knowledge. We present two-dimensional unit structure design of the absorbing layer in IR detectors. A systematic approach is introduced to enhance the absorbing efficiency of incident beam in the near-infrared wavelength range. We derived a layered structure composed of a silicon nitride (Si3N4) layer and an amorphous silicon (a-Si) one in turn by the so called topology optimization in association with the time variant finite element analysis (FEA). It is confirmed that thickness at each layer is in associated with the IR wavelength so that detail dimensions of each layer are inferred. A prototype of the layered structure was fabricated and its performance has been verified through experimental measurement.

Increased in vivo angiogenic effect of glioma stromal mesenchymal stem-like cells on glioma cancer stem cells from patients with glioblastoma.

The presence of glioma stromal mesenchymal stem­like cells (GS-MSLCs) in tumors from glioma patients has been previously reported. The mechanisms through which these cells function as a part of the glioma microenvironment, however, remain incompletely understood. We investigated the biological effects of GS-MSLCs on glioma cancer stem cells (gCSCs), testing the hypothesis that GS-MSLCs alter the biological characteristics of gCSCs. GS-MSLCs and gCSCs were isolated from different glioblastoma (GBM) specimens obtained from patients. In in vitro experiments, gCSCs were cultured alone or co-cultured with GS-MSLCs, and gCSCs cell counts were compared between the two groups. In addition, two groups of orthotopic GBM xenografts in mice were created, one using gCSCs from the monoculture group and one using gCSCs isolated from the co-culture group, and tumor volume and survival were analyzed. Furthermore, in vivo proliferation, apoptosis and vessel formation were examined using immunohistochemical analyses. In vitro cell counts for gCSCs co-cultured with GS-MSLCs increased 3-fold compared to gCSCs cultured alone. In orthotopic xenograft experiments, mice injected with gCSCs isolated from the co-culture group had significantly larger tumor volume, measured on day 40 after injection, and their survival times were shorter. Immunohistochemical analysis showed increased tumor expression of CD31, indicative of enhanced microvessel formation in mice injected with gCSCs co-cultured with GS-MSLCs compared to mice injected with gCSCs cultured alone. However, proliferation (PCNA) and apoptosis (TUNEL) markers showed no significant difference between the two groups. In conclusion, GS-MSLCs may influence the biological properties of gCSCs, shifting them towards a more aggressive status; moreover, increased angiogenesis may be a critical component of this mechanism.