An agarose-based microfluidic platform with a gradient buffer for 3D chemotaxis studies

The current state-of-art in 3D microfluidic chemotaxis device (μFCD) is limited by the inherent coupling of the fluid flow and chemical concentration gradients. Here, we present an agarose-based 3D μFCD that decouples these two important parameters, in that the flow control channels are separated from the cell compartment by an agarose gel wall. This decoupling is enabled by the transport property of the agarose gel, which—in contrast to the conventional microfabrication material such as polydimethylsiloxane (PDMS)—provides an adequate physical barrier for convective fluid flow while at the same time readily allowing protein diffusion. We demonstrate that in this device, a gradient can be pre-established in an agarose layer above the cell compartment (a gradient buffer) before adding the 3D cell-containing matrix, and the dextran (10 kDa) concentration gradients can be re-established within 10 min across the cell-containing matrix and remain stable indefinitely. We successfully quantified the chemotactic response of murine dendritic cells to a gradient of CCL19, an 8.8 kDa lymphoid chemokine, within a type I collagen matrix. This model system is easy to set up, highly reproducible, and will benefit research on 3D chemoinvasion studies, for example with cancer cells or immune cells. Because of its gradient buffering capacity, it is particularly suitable for studying rapidly migrating cells like mature dendritic cells and neutrophils. Electronic Supplementary Material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Ulrike Haessler and Yevgeniy Kalinin have equal contribution.     

Intrinsic single-domain switching in ferroelectric materials on a nearly ideal surface

Ferroelectric domain nucleation and growth in multiferroic BiFeO(3) is studied on a single-domain level by using piezoresponse force spectroscopy. Variation of local electromechanical response with dc tip bias is used to determine the size of the domain formed below the conductive scanning probe tip. The domain parameters are calculated self-consistently from the decoupled Green function theory by using tip geometry determined from the domain wall profile. The critical parameters of the nucleating domain and the activation energy for nucleation are determined. The switching mechanism is modeled by using the phase-field method, and comparison with experimental results shows that the nucleation biases are within a factor of approximately 2 of the intrinsic thermodynamic limit. The role of atomic-scale defects and long-range elastic fields on nucleation bias lowering is discussed. These measurements open a pathway for quantitative studies of the role of a single defect on kinetics and thermodynamics of first order bias-induced phase transitions and electrochemical reactions.     

Assessment of the state of atrial myocardium by two-dimensional grey-scale deformation in patients with arterial hypertension and mild left ventricular hypertrophy

Non-Doppler two-dimensional grey-scale deformation (TGD) is a novel method of assessment of deformation and velocity of deformation of myocardium. TGD allows to evaluate regional and global mechanical function of atria. Aim of our work was to study longitudinal deformation and deformation velocity of the left atrium (LA) and right atrium (RA) in patients with arterial hypertension (AH) and mild left ventricular hypertrophy (LVH). We carried out standard transthoracic echocardiography with subsequent analysis by the TGD method in 30 patients with 1st degree AH and mild LVH. The following measurements were done: maximal longitudinal deformation and maximal velocity of deformation during atrial contractile, reservoir, and conduit phases. We also measured global maximal deformation of LA during its contractile, and reservoir phases. Results of the study showed that changes of parameters of deformation of atrial myocardium developed in patients and mild LVH. Changes of parameters of deformation of LA myocardium were observed in reservoir and conduit phases manifesting as reduced deformation and deformation velocity. Patients with AH and mild LVH had no significant changes of parameters of deformation of atrial myocardium in their contraction phase. Further investigations are required for understanding changes of deformation occurring in myocardium of atria.     

The diagnosis and treatment of enteroparesis in patients with acute pancreatitis

Two leading moments in endotoxicosis of acute pancreatitis pancreatogenic and enterocologenic should be emphasized. A new noninvasive method is proposed for objective determination of the degree of enteroparesis in patients with acute pancreatitis. A conversion of the gastroenterocolonogram curves into digital parameters gave quantitative data which help to reveal the form of acute pancreatitis. the degree of endogenous intoxication and shows the course of the treatment.     

Bacterial hepatocyte growth factor receptor agonist stimulates hepatocyte proliferation and accelerates liver regeneration in a partial hepatectomy rat model

Hepatocyte growth factor (HGF) is central to liver regeneration. The Internalin B (InlB) protein is a virulence factor produced by the pathogenic bacterium Listeria monocytogenes. InlB is known to mimic HGF activity by interacting with the HGF receptor (HGFR) and activating HGFR‐controlled signaling pathways. We expressed and purified the HGFR‐binding InlB domain, InlB321/15, cloned from the fully virulent clinical L. monocytogenes strain. HGFR and Erk1/2 phosphorylation was determined using Western blotting. The capacity of InlB321/15 to bind HGFR was measured using microscale thermophoresis. Liver regeneration was studied in a model of 70% partial hepatectomy (70%PHx) in male Wistar rats. The nuclear grade parameters were quantified using manual (percentage of binuclear hepatocytes), automated (nuclear diameters), or combined (Ki67 proliferation index) scoring methods. Purified InlB321/15 stimulated HGFR and Erk1/2 phosphorylation and accelerated the proliferation of HepG2 cells. InlB321/15 bound HGFR with Kd = 7.4 ± 1.3 nM. InlB321/15 injected intravenously on the second, fourth, and sixth days after surgery recovered the liver mass and improved the nuclear grade parameters. Seven days post 70% PHx, the liver weight indexes were 2.9 and 2.0%, the hepatocyte proliferation indexes were 19.8 and 0.6%, and the percentages of binucleated hepatocytes were 6.7 and 4.0%, in the InlB321/15‐treated and control animals, respectively. Obtained data demonstrated that InlB321/15 improved hepatocyte proliferation and stimulated liver regeneration in animals with 70% hepatectomy.     

Diagnosis, sudden death risk stratification, and treatment of main long QT syndrome molecular-genetic variants

Inherited long QT syndrome (LQTS) refers to the primary electrical diseases of the heart. It is characterized by QT prolongation on resting ECG and syncope due to life-threatening ventricular arrhythmias. This review focuses on diagnosis, differential diagnosis, risk stratification of sudden cardiac death, and treatment strategy of patients with most prevalent genetic fOrms of LQTS - LQT1, LQT2 and LQT3, which accounted for about 90% of all genetically confirmed cases. Recent advances in understanding of relationship between clinical, electrocardiographic features (on ECG, body surface mapping, stress test) and genetic variants of LQT presented. Characteristics of syncopal events and ECG features of LQTl, LQT2 and LQT3 in the majority of cases are helpful to make an appropriate choice for therapy, even before positive result of molecular genetic testing. Management has focused on the use of beta blockers as first-line treatment and exclusion of triggers of life-threatening arrhythmia which are specific for each molecular-genetic variant. Implantation of cardioverter defibrillator for secondary prevention of sudden death in the high-risk patients or patients with insufficient effect of antiarrhythmic therapy is required.