Perfusable Tissue Bioprinted into a 3D-Printed Tailored Bioreactor System

Bioprinting provides a powerful tool for regenerative medicine, as it allows tissue construction with a patient's specific geometry. However, tissue culture and maturation, commonly supported by dynamic bioreactors, are needed. We designed a workflow that creates an implant-specific bioreactor system, which is easily producible and customizable and supports cell cultivation and tissue maturation. First, a bioreactor was designed and different tissue geometries were simulated regarding shear stress and nutrient distribution to match cell culture requirements. These tissues were then directly bioprinted into the 3D-printed bioreactor. To prove the ability of cell maintenance, C2C12 cells in two bioinks were printed into the system and successfully cultured for two weeks. Next, human mesenchymal stem cells (hMSCs) were successfully differentiated toward an adipocyte lineage. As the last step of the presented strategy, we developed a prototype of an automated mobile docking station for the bioreactor. Overall, we present an open-source bioreactor system that is adaptable to a wound-specific geometry and allows cell culture and differentiation. This interdisciplinary roadmap is intended to close the gap between the lab and clinic and to integrate novel 3D-printing technologies for regenerative medicine.

Matrix Metalloproteinase-Responsive Delivery of PEGylated Fibroblast Growth Factor 2

Attachment of polyethylene glycol (PEG) chains is a common, well-studied, and Food and Drug Administration-approved method to address the pharmacokinetic challenges of therapeutic proteins. Occasionally, PEGylation impairs the activity of pharmacodynamics (PD). To overcome this problem, disease-relevant cleavable linkers between the polymer and the therapeutic protein can unleash full PD by de-PEGylating the protein at its target site. In this study, we engineered a matrix metalloproteinase (MMP)-responsive fibroblast growth factor 2 (FGF-2) mutant that was site-specifically extended with a PEG polymer chain. Using bioinspired strategies, the bioconjugate was designed to release the native protein at the desired structure/environment with preservation of the proliferative capacity in vitro on NIH3T3 cells. In vivo, hepatic exposure was diminished but not its renal distribution over time compared to unconjugated FGF-2. By releasing the growth factor from the PEG polymer in response to MMP cleavage, restored FGF-2 may enter hard-to-reach tissues and activate cell surface receptors or nuclear targets.

PEGylation of Human Vascular Endothelial Growth Factor

Vascular endothelial growth factor A-165 (VEGF-A165) positively modulates neointimal hyperplasia, lumen stenosis, and neovascularization. One challenge for the use of VEGF-A165 for potential therapy is its short serum half-life. Therefore, we are designing VEGF-A165 bioconjugates carrying polyethylene glycol (PEG). The purity of the recombinantly expressed human VEGF-A165 exceeded 90%. The growth factor had a half-maximal effective concentration of 0.9 ng/mL (EC50) and induced tube formation of human umbilical vein endothelial cells. PEGylation was conducted by Schiff base reaction followed by reductive amination. After purification, two species were obtained, with one or two PEG attached per VEGF-A165 dimer. Both resulting bioconjugates had a purity exceeding 90%, wild-type bioactivity, and increased hydrodynamic radii as required for prolonging the half-life.

Plant size, latitude, and phylogeny explain within-population variability in herbivory

Interactions between plants and herbivores are central in most ecosystems, but their strength is highly variable. The amount of variability within a system is thought to influence most aspects of plant-herbivore biology, from ecological stability to plant defense evolution. Our understanding of what influences variability, however, is limited by sparse data. We collected standardized surveys of herbivory for 503 plant species at 790 sites across 116° of latitude. With these data, we show that within-population variability in herbivory increases with latitude, decreases with plant size, and is phylogenetically structured. Differences in the magnitude of variability are thus central to how plant-herbivore biology varies across macroscale gradients. We argue that increased focus on interaction variability will advance understanding of patterns of life on Earth.

An exploratory study on the effect of mechanical stress on particle formation in monoclonal antibody infusions

Monoclonal antibody infusions (mAb-i) are administered for the treatment of various diseases. They are often transported over long distances from the compounding site to the site of administration. However, transport studies are typically carried out with the original drug product but not with compounded mAb-i. To address this gap, the impact of mechanical stress on the formation of subvisible/nanoparticles in mAb-i was investigated by dynamic light scattering and flow imaging microscopy. Different mAb-i concentrations were subjected to vibrational orbital shaking and stored at 2-8°C up to 35 days. The screening revealed that pembrolizumab and bevacizumab infusions show the highest propensity for particle formation. Especially bevacizumab at low concentrations exhibited an increase in particle formation. Because of the unknown health risks associated with the long-term application of subvisible particles (SVPs)/nanoparticles in infusion bags, stability studies carried out in the frame of licensing application procedures should also focus on SVP formation in mAb-i. In general, pharmacists should minimize the time of storage and mechanical stress during transport, especially in the case of low-concentrated mAb-i. Moreover, if siliconized syringes are used, they should be washed once with saline solution to minimize particle entry.

Unraveling an Alternative Mechanism in Polymer Self-Assemblies: An Order-Order Transition with Unusual Molecular Interactions between Hydrophilic and Hydrophobic Polymer Blocks

Polymer self-assembly leading to cooling-induced hydrogel formation is relatively rare for synthetic polymers and typically relies on H-bonding between repeat units. Here, we describe a non-H-bonding mechanism for a cooling-induced reversible order-order (sphere-to-worm) transition and related thermogelation of solutions of polymer self-assemblies. A multitude of complementary analytical tools allowed us to reveal that a significant fraction of the hydrophobic and hydrophilic repeat units of the underlying block copolymer is in close proximity in the gel state. This unusual interaction between hydrophilic and hydrophobic blocks reduces the mobility of the hydrophilic block significantly by condensing the hydrophilic block onto the hydrophobic micelle core, thereby affecting the micelle packing parameter. This triggers the order-order transition from well-defined spherical micelles to long worm-like micelles, which ultimately results in the inverse thermogelation. Molecular dynamics modeling indicates that this unexpected condensation of the hydrophilic corona onto the hydrophobic core is due to particular interactions between amide groups in the hydrophilic repeat units and phenyl rings in the hydrophobic ones. Consequently, changes in the structure of the hydrophilic blocks affecting the strength of the interaction could be used to control macromolecular self-assembly, thus allowing for the tuning of gel characteristics such as strength, persistence, and gelation kinetics. We believe that this mechanism might be a relevant interaction pattern for other polymeric materials as well as their interaction in and with biological environments. For example, controlling the gel characteristics could be considered important for applications in drug delivery or biofabrication.

Granular aluminium nanojunction fluxonium qubit

Mesoscopic Josephson junctions, consisting of overlapping superconducting electrodes separated by a nanometre-thin oxide layer, provide a precious source of nonlinearity for superconducting quantum circuits. Here we show that in a fluxonium qubit, the role of the Josephson junction can also be played by a lithographically defined, self-structured granular aluminium nanojunction: a superconductor-insulator-superconductor Josephson junction obtained in a single-layer, zero-angle evaporation. The measured spectrum of the resulting qubit, which we nickname gralmonium, is indistinguishable from that of a standard fluxonium. Remarkably, the lack of a mesoscopic parallel plate capacitor gives rise to an intrinsically large granular aluminium nanojunction charging energy in the range of tens of gigahertz, comparable to its Josephson energy. We measure coherence times in the microsecond range and we observe spontaneous jumps of the value of the Josephson energy on timescales from milliseconds to days, which offers a powerful diagnostics tool for microscopic defects in superconducting materials.

Merging bioresponsive release of insulin-like growth factor I with 3D printable thermogelling hydrogels

3D printing of biomaterials enables spatial control of drug incorporation during automated manufacturing. This study links bioresponsive release of the anabolic biologic, insulin-like growth factor-I (IGF-I) in response to matrix metalloproteinases (MMP) to 3D printing using the block copolymer of poly(2-methyl-2-oxazoline) and thermoresponsive poly(2-n-propyl-2-oxazine) (POx-b-POzi). For that, a chemo-enzymatic synthesis was deployed, ligating IGF-I enzymatically to a protease sensitive linker (PSL), which was conjugated to a POx-b-POzi copolymer. The product was blended with the plain thermogelling POx-b-POzi hydrogel. MMP exposure of the resulting hydrogel triggered bioactive IGF-I release. The bioresponsive IGF-I containing POx-b-POzi hydrogel system was further detailed for shape control and localized incorporation of IGF-I via extrusion 3D printing for future applications in biomedicine and biofabrication.

A thermogelling organic-inorganic hybrid hydrogel with excellent printability, shape fidelity and cytocompatibility for 3D bioprinting

Alginates are the most commonly used bioink in biofabrication, but their rheological profiles makes it very challenging to perform real 3D printing. In this study, an advanced hybrid hydrogel ink was developed, a mixture of thermogelling diblock copolymer, alginate and clay i.e. Laponite XLG. The reversible thermogelling and shear thinning properties of the diblock copolymer in the ink system improves handling and 3D printability significantly. Various three-dimensional constructs, including suspended filaments, were printed successfully with high shape fidelity and excellent stackability. Subsequent ionic crosslinking of alginate fixates the printed scaffolds, while the diblock copolymer is washed out of the structure, acting as a fugitive material on the (macro)molecular level. Finally, cell-laden printing and culture over 21 days demonstrated good cytocompatibility and feasibility of the novel hybrid hydrogels for 3D bioprinting. We believe that the developed material could be interesting for a wide range of bioprinting applications including tissue engineering and drug screening, potentially enabling also other biological bioinks such as collagen, hyaluronic acid, decellularized extracellular matrix or cellulose based bioinks.

Freeform direct laser writing of versatile topological 3D scaffolds enabled by intrinsic support hydrogel

In this study, a novel approach to create arbitrarily shaped 3D hydrogel objects is presented, wherein freeform two-photon polymerization (2PP) is enabled by the combination of a photosensitive hydrogel and an intrinsic support matrix. This way, topologies without physical contact such as a highly porous 3D network of concatenated rings were realized, which are impossible to manufacture with most current 3D printing technologies. Micro-Raman and nanoindentation measurements show the possibility to control water uptake and hence tailor the Young's modulus of the structures via the light dosage, proving the versatility of the concept regarding many scaffold characteristics that makes it well suited for cell specific cell culture as demonstrated by cultivation of human induced pluripotent stem cell derived cardiomyocytes.

From Thermogelling Hydrogels toward Functional Bioinks: Controlled Modification and Cytocompatible Crosslinking

Hydrogels are key components in bioink formulations to ensure printability and stability in biofabrication. In this study, a well-known Diels-Alder two-step post-polymerization modification approach is introduced into thermogelling diblock copolymers, comprising poly(2-methyl-2-oxazoline) and thermoresponsive poly(2-n-propyl-2-oxazine). The diblock copolymers are partially hydrolyzed and subsequently modified by acid/amine coupling with furan and maleimide moieties. While the thermogelling and shear-thinning properties allow excellent printability, trigger-less cell-friendly Diels-Alder click-chemistry yields long-term shape-fidelity. The introduced platform enables easy incorporation of cell-binding moieties (RGD-peptide) for cellular interaction. The hydrogel is functionalized with RGD-peptides using thiol-maleimide chemistry and cell proliferation as well as morphology of fibroblasts seeded on top of the hydrogels confirm the cell adhesion facilitated by the peptides. Finally, bioink formulations are tested for biocompatibility by incorporating fibroblasts homogenously inside the polymer solution pre-printing. After the printing and crosslinking process good cytocompatibility is confirmed. The established bioink system combines a two-step approach by physical precursor gelation followed by an additional chemical stabilization, offering a broad versatility for further biomechanical adaptation or bioresponsive peptide modification.

Field-effect silicon-plasmonic photodetector for coherent T-wave reception

Plasmonic internal photoemission detectors (PIPED) have recently been shown to combine compact footprint and high bandwidth with monolithic co-integration into silicon photonic circuits, thereby opening an attractive route towards optoelectronic generation and detection of waveforms in the sub-THz and THz frequency range, so-called T-waves. In this paper, we further expand the PIPED concept by introducing a metal-oxide-semiconductor (MOS) interface with an additional gate electrode that allows to control the carrier dynamics in the device and the degree of internal photoemission at the metal-semiconductor interfaces. We experimentally study the behavior of dedicated field-effect (FE-)PIPED test structures and develop a physical understanding of the underlying principles. We find that the THz down-conversion efficiency of FE-PIPED can be significantly increased when applying a gate potential. Building upon the improved understanding of the device physics, we further perform simulations and show that the gate field increases the carrier density in the conductive channel below the gate oxide to the extent that the device dynamics are determined by ultra-fast dielectric relaxation rather than by the carrier transit time. In this regime, the bandwidth can be increased to more than 1 THz. We believe that our experiments open a new path towards understanding the principles of internal photoemission in plasmonic structures, leading to PIPED-based optoelectronic signal processing systems with unprecedented bandwidth and efficiency.

Tuning the Thermogelation and Rheology of Poly(2-Oxazoline)/Poly(2-Oxazine)s Based Thermosensitive Hydrogels for 3D Bioprinting

As one kind of "smart" material, thermogelling polymers find applications in biofabrication, drug delivery and regenerative medicine. In this work, we report a thermosensitive poly(2-oxazoline)/poly(2-oxazine) based diblock copolymer comprising thermosensitive/moderately hydrophobic poly(2-N-propyl-2-oxazine) (pPrOzi) and thermosensitive/moderately hydrophilic poly(2-ethyl-2-oxazoline) (pEtOx). Hydrogels were only formed when block length exceeded certain length (≈100 repeat units). The tube inversion and rheological tests showed that the material has then a reversible sol-gel transition above 25 wt.% concentration. Rheological tests further revealed a gel strength around 3 kPa, high shear thinning property and rapid shear recovery after stress, which are highly desirable properties for extrusion based three-dimensional (3D) (bio) printing. Attributed to the rheology profile, well resolved printability and high stackability (with added laponite) was also possible. (Cryo) scanning electron microscopy exhibited a highly porous, interconnected, 3D network. The sol-state at lower temperatures (in ice bath) facilitated the homogeneous distribution of (fluorescently labelled) human adipose derived stem cells (hADSCs) in the hydrogel matrix. Post-printing live/dead assays revealed that the hADSCs encapsulated within the hydrogel remained viable (≈97%). This thermoreversible and (bio) printable hydrogel demonstrated promising properties for use in tissue engineering applications.

An Inverse Thermogelling Bioink Based on an ABA-Type Poly(2-oxazoline) Amphiphile

Hydrogels are key components in several biomedical research areas such as drug delivery, tissue engineering, and biofabrication. Here, a novel ABA-type triblock copolymer comprising poly(2-methyl-2-oxazoline) as the hydrophilic A blocks and poly(2-phenethyl-2-oxazoline) as the aromatic and hydrophobic B block is introduced. Above the critical micelle concentration, the polymer self-assembles into small spherical polymer micelles with a hydrodynamic radius of approx 8-8.5 nm. Interestingly, this specific combination of hydrophilic and hydrophobic aromatic moieties leads to rapid thermoresponsive inverse gelation at polymer concentrations above a critical gelation concentration (20 wt %) into a macroporous hydrogel of densely packed micelles. This hydrogel exhibited pronounced viscoelastic solid-like properties, as well as extensive shear-thinning, rapid structure recovery, and good strain resistance properties. Excellent 3D-printability of the hydrogel at lower temperature opens a wide range of different applications, for example, in the field of biofabrication. In preliminary bioprinting experiments using NIH 3T3 cells, excellent cell viabilities of more than 95% were achieved. The particularly interesting feature of this novel material is that it can be used as a printing support in hybrid bioink systems and sacrificial bioink due to rapid dissolution at physiological conditions.

Development of a 3D printable and highly stretchable ternary organic-inorganic nanocomposite hydrogel

Hydrogels that can be processed with additive manufacturing techniques and concomitantly possess favorable mechanical properties are interesting for many advanced applications. However, the development of novel ink materials with high intrinsic 3D printing performance has been proven to be a major challenge. Herein, a novel 3D printable organic-inorganic hybrid hydrogel is developed from three components, and characterized in detail in terms of rheological property, swelling behavior and composition. The nanocomposite hydrogel combines a thermoresponsive hydrogel with clay LAPONITE® XLG and in situ polymerized poly(N,N-dimethylacrylamide). Before in situ polymerization, the thermogelling and shear thinning properties of the thermoresponsive hydrogel provides a system well-suited for extrusion-based 3D printing. After chemical curing of the 3D-printed constructs by free radical polymerization, the resulting interpenetrating polymer network hydrogel shows excellent mechanical strength with a high stretchability to a tensile strain at break exceeding 550%. Integrating with the advanced 3D-printing technique, the introduced material could be interesting for a wide range of applications including tissue engineering, drug delivery, soft robotics and additive manufacturing in general.

Low dose novel PARP-PI3K inhibition via nanoformulation improves colorectal cancer immunoradiotherapy

Multimodal therapy is often used in oncology to overcome dosing limitations and chemoresistance. Recently, combination immunoradiotherapy has shown great promise in a select subset of patients with colorectal cancer (CRC). Furthermore, molecularly targeted agents delivered in tandem with immunotherapy regimens have been suggested to improve treatment outcomes and expand the population of responding patients. In this study, radiation-sensitizing small molecules niraparib (PARP inhibitor) and HS-173 (PI3K inhibitor) are identified as a novel combination that synergistically enhance toxicity and induce immunogenic cell death both in vitro and in vivo in a CRC model. These inhibitors were co-encapsulated in a polymer micelle to overcome solubility limitations while minimizing off-target toxicity. Mice bearing syngeneic colorectal tumors (CT26) were administered these therapeutic micelles in combination with X-ray irradiation and anti-CTLA-4 immunotherapy. This combination led to enhanced efficacy demonstrated by improved tumor control and increased tumor infiltrating lymphocytes. This report represents the first investigation of DNA damage repair inhibition combined with radiation to potentiate anti-CTLA-4 immunotherapy in a CRC model.

Inverse Thermogelation of Aqueous Triblock Copolymer Solutions into Macroporous Shear-Thinning 3D Printable Inks

Amphiphilic block copolymers that undergo (reversible) physical gelation in aqueous media are of great interest in different areas including drug delivery, tissue engineering, regenerative medicine, and biofabrication. We investigated a small library of ABA-type triblock copolymers comprising poly(2-methyl-2-oxazoline) as the hydrophilic shell A and different aromatic poly(2-oxazoline)s and poly(2-oxazine)s cores B in an aqueous solution at different concentrations and temperatures. Interestingly, aqueous solutions of poly(2-methyl-2-oxazoline)-block-poly(2-phenyl-2-oxazine)-block-poly(2-methyl-2-oxazoline) (PMeOx-b-PPheOzi-b-PMeOx) undergo inverse thermogelation below a critical temperature by forming a reversible nanoscale wormlike network. The viscoelastic properties of the resulting gel can be conveniently tailored by the concentration and the polymer composition. Storage moduli of up to 110 kPa could be obtained while the material retains shear-thinning and rapid self-healing properties. We demonstrate three-dimensional (3D) printing of excellently defined and shape-persistent 24-layered scaffolds at different aqueous concentrations to highlight its application potential, e.g., in the research area of biofabrication. A macroporous microstructure, which is stable throughout the printing process, could be confirmed via cryo-scanning electron microscopy (SEM) analysis. The absence of cytotoxicity even at very high concentrations opens a wide range of different applications for this first-in-class material in the field of biomaterials.

Matrix decoded - A pancreatic extracellular matrix with organ specific cues guiding human iPSC differentiation

The extracellular matrix represents a dynamic microenvironment regulating essential cell functions in vivo. Tissue engineering approaches aim to recreate the native niche in vitro using biological scaffolds generated by organ decellularization. So far, the organ specific origin of such scaffolds was less considered and potential consequences for in vitro cell culture remain largely elusive. Here, we show that organ specific cues of biological scaffolds affect cellular behavior. In detail, we report on the generation of a well-preserved pancreatic bioscaffold and introduce a scoring system allowing standardized inter-study quality assessment. Using multiple analysis tools for in-depth-characterization of the biological scaffold, we reveal unique compositional, physico-structural, and biophysical properties. Finally, we prove the functional relevance of the biological origin by demonstrating a regulatory effect of the matrix on multi-lineage differentiation of human induced pluripotent stem cells emphasizing the significance of matrix specificity for cellular behavior in artificial microenvironments.

Temperature-Dependent Rheological and Viscoelastic Investigation of a Poly(2-methyl-2-oxazoline)-b-poly(2-iso-butyl-2-oxazoline)-b-poly(2-methyl-2-oxazoline)-Based Thermogelling Hydrogel

The synthesis and characterization of an ABA triblock copolymer based on hydrophilic poly(2-methyl-2-oxazoline) (pMeOx) blocks A and a modestly hydrophobic poly(2-iso-butyl-2-oxazoline) (piBuOx) block B is described. Aqueous polymer solutions were prepared at different concentrations (1-20 wt %) and their thermogelling capability using visual observation was investigated at different temperatures ranging from 5 to 80 °C. As only a 20 wt % solution was found to undergo thermogelation, this concentration was investigated in more detail regarding its temperature-dependent viscoelastic profile utilizing various modes (strain or temperature sweep). The prepared hydrogels from this particular ABA triblock copolymer have interesting rheological and viscoelastic properties, such as reversible thermogelling and shear thinning, and may be used as bioink, which was supported by its very low cytotoxicity and initial printing experiments using the hydrogels. However, the soft character and low yield stress of the gels do not allow real 3D printing at this point.

Structure and nucleic acid binding properties of KOW domains 4 and 6-7 of human transcription elongation factor DSIF

The human transcription elongation factor DSIF is highly conserved throughout all kingdoms of life and plays multiple roles during transcription. DSIF is a heterodimer, consisting of Spt4 and Spt5 that interacts with RNA polymerase II (RNAP II). DSIF binds to the elongation complex and induces promoter-proximal pausing of RNAP II. Human Spt5 consists of a NusG N-terminal (NGN) domain motif, which is followed by several KOW domains. We determined the solution structures of the human Spt5 KOW4 and the C-terminal domain by nuclear magnetic resonance spectroscopy. In addition to the typical KOW fold, the solution structure of KOW4 revealed an N-terminal four-stranded β-sheet, previously designated as the KOW3-KOW4 linker. In solution, the C-terminus of Spt5 consists of two β-barrel folds typical for KOW domains, designated KOW6 and KOW7. We also analysed the nucleic acid and RNAP II binding properties of the KOW domains. KOW4 variants interacted with nucleic acids, preferentially single stranded RNA, whereas no nucleic acid binding could be detected for KOW6-7. Weak binding of KOW4 to the RNAP II stalk, which is comprised of Rpb4/7, was also detected, consistent with transient interactions between Spt5 and these RNAP II subunits.

Characterization of a submicro-X-ray fluorescence setup on the B16 beamline at Diamond Light Source

An X-ray fluorescence setup has been tested on the B16 beamline at the Diamond Light Source synchrotron with two different excitation energies (12.7 and 17 keV). This setup allows the scanning of thin samples (thicknesses up to several micrometers) with a sub-micrometer resolution (beam size of 500 nm × 600 nm determined with a 50 µm Au wire). Sensitivities and detection limits reaching values of 249 counts s^-1 fg^-1 and 4 ag in 1000 s, respectively (for As Kα excited with 17 keV), are presented in order to demonstrate the capabilities of this setup. Sample measurements of a human bone and a single cell performed at B16 are presented in order to illustrate the suitability of the setup in biological applications.

Drug Specificity, Synergy and Antagonism in Ultrahigh Capacity Poly(2-oxazoline)/Poly(2-oxazine) based Formulations

Polymer micelles offer the possibility to create a nanoscopic environment that is distinct from the bulk phase. They find applications in catalysis, drug delivery, cleaning, etc. Often, one simply distinguishes between hydrophilic and hydrophobic, but fine-tuning of the microenvironment is possible by adjusting the structure of the polymer amphiphile. Here, we investigated a small library of structurally similar amphiphiles based on poly(2-oxazoline)s and poly(2-oxazine)s with respect to their solubilization capacity for two extremely water insoluble drugs, curcumin and paclitaxel. We found very significant and orthogonal specificities even if only one methylene group is exchanged between the polymer backbone and side chain. More strikingly, we observed profound synergistic and antagonistic solubilization patterns for the coformulation of the two drugs. Our findings shed new light on host-guest interaction in polymer micelles and such pronounced host-guest specificities in polymer micelles may not only be interesting in drug delivery but also for applications such as micellar catalysis.

Both the cutaneous sensation and phosphene perception are modulated in a frequency-specific manner during transcranial alternating current stimulation

PURPOSE

Transcranial alternating current stimulation (tACS) is a non-invasive stimulation technique for shaping neuroplastic processes and possibly entraining ongoing neural oscillations in humans. Despite the growing number of studies using tACS, we know little about the procedural sensations caused by stimulation. In order to fill this gap, we explored the cutaneous sensation and phosphene perception during tACS.

METHODS

Twenty healthy participants took part in a randomized, single-blinded, sham-controlled study, where volunteers received short duration stimulation at 1.0 mA intensity between 2 to 250 Hz using the standard left motor cortex-contralateral supraorbital montage. We recorded the perception onset latency and the strength of the sensations assessed by visual rating scale as dependent variables.

RESULTS

We found that tACS evoked both cutaneous sensation and phosphene perception in a frequency-dependent manner. Our results show that the most perceptible procedural sensations were induced in the beta and gamma frequency range, especially at 20 Hz, whereas minimal procedural sensations were indicated in the ripple range (140 and 250 Hz).

CONCLUSIONS

We believe that our results provide a relevant insight into the procedural sensations caused by oscillatory currents, and will offer a basis for developing more sophisticated stimulation protocols and study designs for future investigations.

Persistência de patógenos e do antibiótico salinomicina em pilhas de compostagem de cama de aviário

A cama de aviário pode causar contaminação ambiental pelo excesso de nutrientes, microor-ganismos patogênicos e resíduos químicos. Para minimizar estes impactos pode-se fazer compos-tagem da cama de aviário antes de sua aplicação como fertilizante, porém, ainda existem muitas dúvidas sobre a eficiência deste tratamento. O objetivo deste trabalho foi analisar a persistência de patógenos e do antibiótico salinomicina em cama de aviário submetida à pilhas estáticas de compostagem. Os três tratamentos usados foram: CSC (cama de aviário com camadas de solo e coberto com capim) CP (cama de aviário coberta com polietileno) e CCC (cama de aviário com camadas de capim e coberto com capim). Acompanhou-se a evolução da temperatura nas pilhas, pH, níveis de Escherichia coli, oocistos de eimérias e concentrações do antibiótico salino-micina. O tratamento CP foi o menos eficiente na degradação do antibiótico salinomicina até os 90 dias. A compostagem da cama de aviário, independente dos tratamentos, é eficiente na eliminação de E. coli.

A novel method to identify gene–gene effects in nuclear families: the MDR-PDT

It is now well recognized that gene-gene and gene-environment interactions are important in complex diseases, and statistical methods to detect interactions are becoming widespread. Traditional parametric approaches are limited in their ability to detect high-order interactions and handle sparse data, and standard stepwise procedures may miss interactions that occur in the absence of detectable main effects. To address these limitations, the multifactor dimensionality reduction (MDR) method [Ritchie et al., 2001: Am J Hum Genet 69:138-147] was developed. The MDR is well-suited for examining high-order interactions and detecting interactions without main effects. The MDR was originally designed to analyze balanced case-control data. The analysis can use family data, but requires a single matched pair be selected from each family. This may be a discordant sib pair, or may be constructed from triad data when parents are available. To take advantage of additional affected and unaffected siblings requires a test statistic that measures the association of genotype with disease in general nuclear families. We have developed a novel test, the MDR-PDT, by merging the MDR method with the genotype-Pedigree Disequilibrium Test (geno-PDT)[Martin et al., 2003: Genet Epidemiol 25:203-213]. MDR-PDT allows identification of single-locus effects or joint effects of multiple loci in families of diverse structure. We present simulations to demonstrate the validity of the test and evaluate its power. To examine its applicability to real data, we applied the MDR-PDT to data from candidate genes for Alzheimer disease (AD) in a large family dataset. These results show the utility of the MDR-PDT for understanding the genetics of complex diseases.

Fracture characteristics of carbon fibre, ceramic and non-palladium endodontic post systems at monotonously increasing loads

A carbon fibre post system, three non-palladium and one palladium metal post systems, two ceramic post systems, and a metal post system with a ceramic core were studied in vitro. The control group consisted of root-filled test teeth without posts. The test teeth were identical artificial roots of an upper central incisor made from a posterior composite whose module of elasticity was similar to that of natural dentine. All posts were cemented in the roots using Panavia 21 TC. Subsequently, standardized full crowns were cemented onto all roots. On a universal testing machine, the test teeth were loaded palatally at monotonously increasing loads until root fracture. The highest mean fracture loads were found for the carbon fibre post system (312.5 +/- 58.8 N). The fracture load of non-palladium metal posts (242.3-300.4 N) did not differ significantly from that of the Perma-dor post (265.9 N), which does contain palladium. Values of 300.3 +/- 89.3 N (aluminium oxide ceramics) and 193.5 +/-57.0 N (zirconia ceramics) were found for the ceramic posts. The control group exhibited a fracture load of 228.8 +/- 35.7 N. The mean distance between the vestibular end of the fracture gap and the point of force application was between 10.1 +/- 2.3 and 14.7 +/- 1.2 mm.

[Chronic pelvic pain in women. A condition difficult to diagnose--more than 70 different diagnoses can be considered]

Chronic pelvic pain, CPP, with a prevalence of about 15 percent of the female population between 18 and 50 years, has vast psychosocial and economic consequences. The cause(s) are often elusive despite invasive procedures including laparoscopy. There is a connection between CPP and abuse in childhood, sexual as well as non-sexual. Usually the woman initially seeks a gynecologist, who should have some knowledge also of lesser known causes of CPP such as pelvic congestion and nerve entrapments. A multidisciplinary approach can offer more possibilities to reach a plausible diagnosis and adequate treatment.