Structural maturation of myofilaments in engineered 3D cardiac microtissues characterized using small angle x-ray scattering

Understanding the structural and functional development of human-induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs) is essential to engineering cardiac tissue that enables pharmaceutical testing, modeling diseases, and designing therapies. Here we use a method not commonly applied to biological materials, small angle x-ray scattering, to characterize the structural development of hiPSC-CMs within three-dimensional engineered tissues during their preliminary stages of maturation. An x-ray scattering experimental method enables the reliable characterization of the cardiomyocyte myofilament spacing with maturation time. The myofilament lattice spacing monotonically decreases as the tissue matures from its initial post-seeding state over the span of 10 days. Visualization of the spacing at a grid of positions in the tissue provides an approach to characterizing the maturation and organization of cardiomyocyte myofilaments and has the potential to help elucidate mechanisms of pathophysiology, and disease progression, thereby stimulating new biological hypotheses in stem cell engineering.

Modal engineering of electromagnetic circuits to achieve rapid settling times

Inductive circuits and devices are ubiquitous and important design elements in many applications, such as magnetic drives, galvanometers, magnetic scanners, applying direct current (DC) magnetic fields to systems, radio frequency coils in nuclear magnetic resonance (NMR) systems, and a vast array of other applications. They are widely used to generate both DC and alternating current (AC) magnetic fields. Many of these applications require a rapid step and settling time, turning the DC or AC magnetic field on and off quickly. The inductive response normally makes this a challenging thing to do. In this article, we discuss open loop control algorithms for achieving rapid step and settling times in four general categories of applications: DC and AC systems where the system is either under- or over-damped. Each of these four categories requires a different algorithm, which we describe here. We show the operation of these drive methods using Simulink and Simscape modeling tools, analytical solutions to the underlying differential equations, and experimental results using an inductive magnetic coil and a Hall sensor. Finally, we demonstrate the application of these techniques to significantly reduce ringing in a standard NMR circuit. We intend this article to be practical, with useful, easy-to-apply algorithms and helpful tuning tricks.

The Integration of Optical Stimulation in a Mechanically Dynamic Cell Culture Substrate

A cell culture well with integrated mechanical and optical stimulation is presented. This is achieved by combining dielectric elastomer soft actuators, also known as artificial muscles, and a varifocal micro-electromechanical mirror that couples light from an optical fiber and focuses it onto the transparent cell substrate. The device enables unprecedented control of in vitro cell cultures by allowing the experimenter to tune and synchronize mechanical and optical stimuli, thereby enabling new experimental assays in optogenetics, fluorescent microscopy, or laser stimulation that include dynamic mechanical strain as a controlled input parameter.

Analysis of a Casimir-driven parametric amplifier with resilience to Casimir pull-in for MEMS single-point magnetic gradiometry

The Casimir force, a quantum mechanical effect, has been observed in several microelectromechanical system (MEMS) platforms. Due to its extreme sensitivity to the separation of two objects, the Casimir force has been proposed as an excellent avenue for quantum metrology. Practical application, however, is challenging due to attractive forces leading to stiction and device failure, called Casimir pull-in. In this work, we design and simulate a Casimir-driven metrology platform, where a time-delay-based parametric amplification technique is developed to achieve a steady-state and avoid pull-in. We apply the design to the detection of weak, low-frequency, gradient magnetic fields similar to those emanating from ionic currents in the heart and brain. Simulation parameters are selected from recent experimental platforms developed for Casimir metrology and magnetic gradiometry, both on MEMS platforms. While a MEMS offers many advantages to such an application, the detected signal must typically be at the resonant frequency of the device, with diminished sensitivity in the low frequency regime of biomagnetic fields. Using a Casimir-driven parametric amplifier, we report a 10,000-fold improvement in the best-case resolution of MEMS single-point gradiometers, with a maximum sensitivity of 6 Hz/(pT/cm) at 1 Hz. Further development of the proposed design has the potential to revolutionize metrology and may specifically enable the unshielded monitoring of biomagnetic fields in ambient conditions.

Autoinflammatory process in the pathogenesis of generalized pustular psoriasis and perspectives of its targeted therapy

The dysregulated inflammatory process not only plays an important role in the development of chronic plaque psoriasis but also is a major pathogenetic mechanism behind the generalized pustular psoriasis (GPP) and other rare pustular forms of the disease. The key players in this process are the cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF), IL-12/23, IL-17A and especially IL-36. Their excessive activity or production in some GPP patients is due to mutations in genes that encode molecules involved in inhibiting the action of IL-36 (IL-36Ra) or in intracellular inflammatory signaling (CARD14, AP1S3). Knowledge about the pathological role of inflammatory cytokines in the development of pustular forms of psoriasis has also found application in their biological therapy with monoclonal antibodies that neutralize the action of IL-12/23, IL-17A, TNF or IL-1β. Other promising agents are monoclonal antibodies against the interleukin 36 receptor, which have already successfully gone through the first phases of clinical trials and are currently being tested for their long-term efficacy, safety and tolerability.

Probing the subcellular nanostructure of engineered human cardiomyocytes in 3D tissue

The structural and functional maturation of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is essential for pharmaceutical testing, disease modeling, and ultimately therapeutic use. Multicellular 3D-tissue platforms have improved the functional maturation of hiPSC-CMs, but probing cardiac contractile properties in a 3D environment remains challenging, especially at depth and in live tissues. Using small-angle X-ray scattering (SAXS) imaging, we show that hiPSC-CMs matured and examined in a 3D environment exhibit a periodic spatial arrangement of the myofilament lattice, which has not been previously detected in hiPSC-CMs. The contractile force is found to correlate with both the scattering intensity (R ² = 0.44) and lattice spacing (R ² = 0.46). The scattering intensity also correlates with lattice spacing (R ² = 0.81), suggestive of lower noise in our structural measurement than in the functional measurement. Notably, we observed decreased myofilament ordering in tissues with a myofilament mutation known to lead to hypertrophic cardiomyopathy (HCM). Our results highlight the progress of human cardiac tissue engineering and enable unprecedented study of structural maturation in hiPSC-CMs.

Advancing Roles of Healthcare Professionals in Palliative Radiotherapy

New methods of working in relation to the management of patients requiring palliative radiotherapy are being embraced in hospital departments around the world. Team members are expanding on their previously assigned scope of practice to take on duties that had previously only been assigned to a consultant clinical oncologist. Career frameworks such as the four-tier model have been built upon to identify the skills held by other healthcare professionals and show how they may be best placed to take on additional roles within a patient pathway. Experiences of four departments in different countries report their local experiences in using both therapeutic radiographers and nursing staff to undertake advanced and consultant-level practice in relation to the management of both palliative radiotherapy patients and their research work streams. Involvement of other healthcare professionals within the clinical or research pathway for the management of palliative radiotherapy patients can be achieved. Their involvement can support clinicians and help to ensure the safe and efficient management of patients requiring palliative radiotherapy.

100 pT/cm single-point MEMS magnetic gradiometer from a commercial accelerometer

Magnetic sensing is present in our everyday interactions with consumer electronics and demonstrates the potential for the measurement of extremely weak biomagnetic fields, such as those of the heart and brain. In this work, we leverage the many benefits of microelectromechanical system (MEMS) devices to fabricate a small, low-power, and inexpensive sensor whose resolution is in the range of biomagnetic fields. At present, biomagnetic fields are measured only by expensive mechanisms such as optical pumping and superconducting quantum interference devices (SQUIDs), suggesting a large opportunity for MEMS technology in this work. The prototype fabrication is achieved by assembling micro-objects, including a permanent micromagnet, onto a postrelease commercial MEMS accelerometer using a pick-and-place technique. With this system, we demonstrate a room-temperature MEMS magnetic gradiometer. In air, the sensor's response is linear, with a resolution of 1.1 nT cm^-1, spans over 3 decades of dynamic range to 4.6 µT cm^-1, and is capable of off-resonance measurements at low frequencies. In a 1 mTorr vacuum with 20 dB magnetic shielding, the sensor achieves a 100 pT cm^-1 resolution at resonance. This resolution represents a 30-fold improvement compared with that of MEMS magnetometer technology and a 1000-fold improvement compared with that of MEMS gradiometer technology. The sensor is capable of a small spatial resolution with a magnetic sensing element of 0.25 mm along its sensitive axis, a >4-fold improvement compared with that of MEMS gradiometer technology. The calculated noise floor of this platform is 110 fT cm^-1 Hz^-1/2, and thus, these devices hold promise for both magnetocardiography (MCG) and magnetoencephalography (MEG) applications.

Extreme angle, tip-tilt MEMS micromirror enabling full hemispheric, quasi-static optical coverage

Beam steering is essential for a variety of optical applications such as communication, LIDAR, and imaging. Microelectromechanical system (MEMS) mirrors are an effective method of achieving modest speeds and angular range at low cost. Typically there are a number of tradeoffs considered when designing a tip-tilt mirror, such as tilt angle and speed. For example, many mirrors are designed to scan at their resonant frequency to achieve large angles. This is effective for a scanning mode; however, this makes the device slow and ineffective as a galvo (quasi-static). Here, we present a magnetic MEMS mirror with extreme quasi-static mechanical tilt angles of ±60° (±120° optical) about two rotation axes. This micromirror enables full hemispheric optical coverage without compromising speed; settling in 4.5 ms using advanced drive techniques. This mirror will enable new applications for MEMS micromirrors previously thought impossible due to their limited angular range and speed.

Building a Casimir metrology platform with a commercial MEMS sensor

The Casimir Effect is a physical manifestation of quantum fluctuations of the electromagnetic vacuum. When two metal plates are placed close together, typically much less than a micron, the long wavelength modes between them are frozen out, giving rise to a net attractive force between the plates, scaling as d ^-4 (or d ^-3 for a spherical-planar geometry) even when they are not electrically charged. In this paper, we observe the Casimir Effect in ambient conditions using a modified capacitive micro-electromechanical system (MEMS) sensor. Using a feedback-assisted pick-and-place assembly process, we are able to attach various microstructures onto the post-release MEMS, converting it from an inertial force sensor to a direct force measurement platform with pN (piconewton) resolution. With this system we are able to directly measure the Casimir force between a silver-coated microsphere and gold-coated silicon plate. This device is a step towards leveraging the Casimir Effect for cheap, sensitive, room temperature quantum metrology.

Design and characterization of an electromagnetic probe for distinguishing morphological differences in soft tissues

We present a method for designing and optimizing an in-house designed electromagnetic probe for distinguishing morphological differences in biological tissues. The probe comprises concentric multi-wound coils, the inner being the primary coil and the outer being the detector coil. A time-varying voltage is imposed on the primary coil, resulting in an induced current in the detector coil. For highly conductive samples, eddy currents are induced in the sample and inductively couple with the electromagnetic probe. However, in weakly conducting samples, the primary coupling mechanism is found to be capacitive though there can be a non-negligible inductive component. Both the mutual inductive coupling and the capacitive coupling between the sample and the probe are detected as a change in the induced voltage of the detector coil using lock-in detection. The induced voltage in the detector coil is influenced more by the morphological structure of the specimen rather than by changes in electrical conductivity within different regions of the sample. The instrument response of the lock-in amplifier is also examined with simulated input voltage signals to relate its output to specific changes in inductive and capacitive coupling, in order to relate sample characteristics to a single voltage output. A circuit element model is used to interpret the experimental measurements. It is found that the sensitivity of the measurement for a given set of probe characteristics (resistances, inductances, and capacitances) can be optimized by adding a small amount of capacitance in the external circuit in parallel with the detector coil. Illustrative measurements are presented on animal (porcine and bovine) tissue and on human liver tissue containing a metastatic tumor to demonstrate the capabilities of the probe and measurement method in distinguishing different tissue types despite having similar electrical conductivities. Since biological tissues are multi-scale, heterogeneous materials comprising regions of differing conductivity, permittivity, and morphological structure, the electromagnetic method presented here has the potential to examine structural variations in tissue undergoing physical changes due to healing or disease.

VLA4 Gene Polymorphism and Susceptibility to Multiple Sclerosis in Slovaks

Multiple sclerosis (MS) is an inflammatory autoimmune disease occurring in genetically sensitive individuals. As migration of immune cells into the CNS is facilitated by the Very Late Antigen 4 (VLA-4) integrin molecule, the VLA4 gene may be considered as a plausible candidate genetic risk factor for susceptibility to MS. Therefore, the objective of our study was to investigate the association between two genetic polymorphisms located in the VLA4 gene and the risk of multiple sclerosis. One hundred seventeen MS patients and 165 control subjects from Slovakia were genotyped for VLA4 gene SNP polymorphisms at positions 269 (C/A) and 3061 (A/G). The same study cohorts were also genotyped for the rs3135388 polymorphism tagging the HLA-DRB1*15:01 allele, which is a known genetic factor associated with susceptibility to develop MS in many populations. Our findings show for the first time that the rs3135388 polymorphism is a strong risk factor for MS in the Slovak population. Investigation of the VLA4 gene polymorphisms revealed a significantly higher frequency of the 3061AG genotype in MS patients compared to the controls (P ≤ 0.05). We suggest that the 3061AG polymorphic variant is an independent genetic risk factor for MS development in our population as it was significantly associated with this disease. The association was also confirmed after applying multivariate logistic-regression analysis adjusted for gender, age and HLA-DRB1*15:01 positivity as possible influencing factors.

High susceptibility to pemphigus vulgaris due to HLA-DRB1*14:54 in the Slovak population

The current work describes an association between pemphigus vulgaris (PV) and class II HLA alleles in the Slovak population, the first such study in Slovakia on the 'high-resolution level'. This work takes into account the new HLA allele nomenclature, officially adopted in 2010. In particular, we have focused on the associations between PV and DRB1*14:54 and DRB1*14:01. This case-control study was performed in a cohort of 43 PV Caucasian patients and 113 Caucasian control subjects from Slovakia. HLA typing was performed using PCR-SSP (polymerase chain reaction with sequence-specific primers). We found significantly positive associations between PV and the HLA alleles DRB1*04:02, DRB1*04:04, DRB1*14:54, DRB1*14:04, DRB1*14:05, DQB1*03:02 and DQB1*05:03. In contrast, HLA-DQB1*06, DRB1*07 and DRB1*13 were negatively associated with PV. Importantly, 93% of PV patients possessed at least one of two HLA haplotypes, DRB1*04-DQB1*03 or HLA-DRB1*14-DQB1*05. We confirmed the previously reported associations between HLA class II alleles and PV and described a new association between PV and DRB1*14:54. This allele was first described in 2005, and there has been only one report of its association with PV to date.

Genetic variations of interleukin-8, CXCR1 and CXCR2 genes and risk of acute pyelonephritis in children

Acute pyelonephritis (APN) is the most severe form of urinary tract infection, the etiopathogenesis of which is still not well understood. Previous studies demonstrated that chemotaxis of neutrophils into the tissue and across the infected epithelial layer is a key step in rapid bacterial clearance. Variations within genes encoding the major chemokine interleukin-8 and its receptors CXCR1 and CXCR2 are therefore attractive candidates for participation in genetic predisposition to APN. The aim of our study was to evaluate the association of single nucleotide polymorphisms (SNPs) -251 T/A, +781 C/T, +1633 C/T and +2767 A/T in the IL-8 gene, +2608 G/C in the CXCR1 gene and +1208 C/T in the CXCR2 gene with susceptibility to APN in the Slovak population. PCR-SSP and PCR-RFLP were used to genotype SNPs in 147 children with APN (62 with recurrent and 85 with episodic form) and 215 healthy individuals. Statistical analysis revealed significantly increased frequency of CXCR1 +2608 C allele (P = 0.0238, OR = 2.452, 95% CI = 1.147-5.243) and GC genotype (P = 0.0201, OR = 2.627, 95% CI = 1.188-5.810) and lower frequency of CXCR2 +1208 T allele (P = 0.0408, OR = 0.645, 95% CI = 0.429-0.972) and TT+TC genotypes (P = 0.0497, OR = 0.5273, 95% CI = 0.288-0.964) in patients with recurrent APN compared with healthy controls. Furthermore, the A allele of IL-8 -251 T/A SNP was also significantly overrepresented in patients with recurrent APN when compared with those with only single episode of APN (P = 0.0439, OR = 1.627, 95% CI = 1.019-2.599). Our results indicate that the minor CXCR1 +2608 C allele is associated with significantly increased susceptibility to APN in childhood, while the CXCR2 +1208 T allele confers protection from recurrent APN. Moreover, allele A of the IL-8 -251 T/A may also increase the risk of developing recurrent attacks after the first-time APN.

TNF-alpha and IL-10 gene polymorphisms show a weak association with pemphigus vulgaris in the Slovak population

BACKGROUND

Pemphigus vulgaris is a rare chronic autoimmune disease of skin and mucous membranes, with several cytokines participating in its development. The role of their gene polymorphisms in susceptibility to the disease is, however, not fully understood.

OBJECTIVE

The aim of our case-control study was to investigate whether some of 22 single nucleotide polymorphisms (SNPs) in 13 cytokine genes (IL-1alpha, IL-1beta, IL-1RI, IL-1Ra, IL-4Ralpha, IL-12, IFN-gamma, TGF-beta1, TNF-alpha, IL-2, IL-4, IL-6 and IL-10) are associated with pemphigus vulgaris in the Slovak population.

METHODS

DNA samples were obtained from 34 pemphigus vulgaris patients and 140 healthy controls of Slovak origin. Cytokine gene SNPs were determined using the polymerase chain reaction with sequence-specific primers (PCR-SSP) method. Results We found a weak association between pemphigus vulgaris and polymorphic variants in TNF-alpha and IL-10 genes only, with haplotypes TNF-alpha-308G/-238G and IL-10 -1082A/-819C/-592C being significantly overrepresented in pemphigus vulgaris patients (TNF-alpha GG: 94.12% vs. 82.86%, P = 0.0216; IL-10 ACC: 44.12% vs. 30.00%, P = 0.0309).

CONCLUSIONS

Our preliminary results suggest that certain TNF-alpha and IL-10 gene polymorphisms might contribute to genetic susceptibility to pemphigus vulgaris; however, their overall impact on disease development will be rather limited.

Single nucleotide polymorphisms of cytokine genes in the healthy Slovak population

Cytokines are molecules that control and modulate the activities of numerous target cells via binding to specific receptors. The observed differences in the cytokine production among individuals can be, at least partially, explained by gene polymorphisms. Several cytokine gene polymorphisms have been identified to play a role in susceptibility to various diseases, including autoimmune, infectious, allergic or cardiovascular diseases. The aim of the current study was to determine allele and genotype frequencies of 22 polymorphisms in 13 cytokine genes in the healthy Slovak population and to compare them with data available from six populations from Central and Southern Europe. A polymerase chain reaction with sequence-specific primers was used to genotype polymorphisms within genes encoding IL-1alpha, IL-1beta, IL-1R, IL-1RA, IL-4Ralpha, IL-12, IFN-gamma, TGF-beta, TNF-alpha, IL-2, IL-4, IL-6 and IL-10 in a sample of 140 unrelated Slovak subjects. The allelic distribution of all polymorphisms in the Slovak population was very close to that in the geographically and historically closest populations in Central Europe--the Czech and the Polish. However, several differences were found between the Slovak and four populations from Southern Europe. The obtained data represent a basis for further studies on association of cytokine gene polymorphisms with some diseases.

Associations between HLA class II alleles and type 1 diabetes mellitus in the Slovak population

OBJECTIVES

Several associations between HLA complex and diabetes mellitus type IA were found in various groups of patients of Caucasoid population. This study was therefore prompted to be conducted in Slovak population, since any such has not yet been performed in Slovak population.

METHODS

Patients suffering from DM-1A originated from all regions of Slovakia. Their age ranged from 1 to 42 years; but the criterion for including the subject to the study was the definition of diagnosis in older patients before their age of 15 (Table 1). The diagnosis was set up according to internationally accepted criteria. A total of 460 patients was typed for HLA-DQB1 alleles, among them 97 also for HLA-DQA1 and 146 for HLA-DRB1 alleles. HLA-typing was performed by a PCR-SSP method. Control group consisted of 196 (DQA), 143 (DQB1) and 130 (DRB1) unrelated blood donors aged 19-55 years old irrespective of their age or sex. The data obtained were expressed in a 2 x 2 contingency table and statistical significance was calculated by the Fisher exact test.

RESULTS

Among 11 HLA-DQB1 alleles tested DOB1*0302 was the most frequent in DM-1A patients (30.33% vs. 5.59% in healthy subjects (HS), followed by DQB1*0201 (22.93% vs. 12.94%, respectively). In contrast, the frequency rate of DQB1*0301 (10.66% vs. 24.48%), DOB1*0602 (2.17% vs. 10.14%) and DQB1*0603 (2.5% vs. 8.39 %) were decreased in DM-1A patients. Out of 14 DQA1 alleles the highest occurrence rate showed DQA1*0301 (30.93% vs. 17.09) and DQA1*0501 (34.02% vs. 25.76%), while DQA1*0102 (8.76% vs. 16.58%) and DQA1*0201 (6.18 % vs. 13.51%7), respectively, were found to be the least frequent. Among 13 HLA-DRB1 alleles tested, the most common occurrence rates showed DRB1*03 (26.37% vs. 9.62%) and DRB1*04 (7.19% vs. 14.23%), while the least frequent alleles were DRB 1*15 (2.74% vs. 12.31%), DRB1*07 (7.19% vs. 14.23%), and DRB1*11 (2.74% vs. 20.38%). The alleles DQB1*0302 and DQA1*0301, respectively, were present in the same individual in all DRB1*04 positive patients, suggesting that they belong to the haplotype. Similar situation was observed with the alleles DQB1*0201, DQA1*0501, and DRB*0301, respectively, forming the second HLA haplotype so characteristic for DM1A.