Multilayer composite scaffolds with mechanical properties similar to small intestinal submucosa

Use of biodegradable scaffolds to engineer new tissues has become an attractive option in various transplantation protocols. In particular, small intestinal submucosa (SIS) has generated immense interest in various tissue engineering applications because of its diverse favorable properties. However, it is a natural matrix, which leads to problems in large-scale preparations and contains sample to sample heterogeneity. In this study, we explored the formation of synthetic matrix mimicking the characteristics of the SIS. Three-dimensional composite structures were developed by sandwiching 50:50 PLGA film between porous chitosan matrices. The outer chitosan layers provide biological activity while the inner PLGA layer provides mechanical strength. PLGA films were initially perforated at 1 cm distance, and the porous chitosan matrix was formed sequentially on each side by controlled rate freezing and lyophilization technique at -80 degrees C. Scanning electron microscopy analysis showed a layered microarchitecture with chitosan filling the perforations of PLGA membrane. Urea permeability studies confirmed that the perforations were filled (negligible urea transfer across composite over 8 h). Tensile strength analysis showed that the matrices formed using 160 kDa PLGA had sufficient break stress ( approximately 4.5 MPa). Degradation analysis over 8 weeks in the presence of 10 mg/L lysozyme showed a 50% decrease in total weight and an 80% decrease in PLGA molecular weight. When cellular adhesion and actin distribution of mouse embryonic fibroblasts were evaluated, for 7 days, cells showed their typical spindle shape and redistribution of actin fibers on composite matrices. Viability studies and MMP-2/MMP-9 activity showed that the cells were viable and functional, similar to tissue culture plastic. Further, canine bladder smooth muscle cells also showed similar cell adhesion and spreading on the composite matrix. In summary, composite structures mimicking SIS were constructed and show potential as a tissue engineering material.     

Medication adherence as a learning process: insights from cognitive psychology

Non-adherence to medications is one of the largest contributors to sub-optimal health outcomes. Many theories of adherence include a ‘value–expectancy’ component in which a patient decides to take a medication partly based on expectations about whether it is effective, necessary, and tolerable. We propose reconceptualising this common theme as a kind of ‘causal learning’ – the patient learns whether a medication is effective, necessary, and tolerable, from experience with the medication. We apply cognitive psychology theories of how people learn cause–effect relations to elaborate this causal-learning challenge. First, expectations and impressions about a medication and beliefs about how a medication works, such as delay of onset, can shape a patient’s perceived experience with the medication. Second, beliefs about medications propagate both ‘top-down’ and ‘bottom-up’, from experiences with specific medications to general beliefs about medications and vice versa. Third, non-adherence can interfere with learning about a medication, because beliefs, adherence, and experience with a medication are connected in a cyclic learning problem. We propose that by conceptualising non-adherence as a causal-learning process, clinicians can more effectively address a patient’s misconceptions and biases, helping the patient develop more accurate impressions of the medication.     

Free-breathing 3D diffusion MRI for high-resolution hepatic metastasis characterization in small animals

The goal of this study was to develop a 3D diffusion weighted sequence for free breathing liver imaging in small animals at high magnetic field. Hepatic metastases were detected and the apparent diffusion coefficients (ADC) were measured. A 3D SE-EPI sequence was developed by (i) inserting a water-selective excitation radiofrequency pulse to suppress adipose tissue signal and (ii) bipolar diffusion gradients to decrease the sensitivity to respiration motion. Mice with hepatic metastases were imaged at 7T by applying b values from 200 to 1100 s/mm². 3D images with high spatial resolution (182 × 156 × 125 µm) were obtained in only 8 min 32 s. The modified DW-SE-EPI sequence allowed to obtain 3D abdominal images of healthy mice with fat SNR 2.5 times lower than without any fat suppression method and sharpness 2.8 times higher than on respiration-triggered images. Due to the high spatial resolution, the core and the periphery of disseminated hepatic metastases were differentiated at high b-values only, demonstrating the presence of edema and proliferating cells (with ADC of 2.65 × 10^?3 and 1.55 × 10^?3 mm²/s, respectively). Furthermore, these metastases were accurately distinguished from proliferating ones within the same animal at high b-values (mean ADC of 0.38 × 10^?3 mm²/s). Metastases of less than 1.7 mm³ diameter were detected. The new 3D SE-EPI sequence enabled to obtain diffusion information within liver metastases. In addition of intra-metastasis heterogeneity, differences in diffusion were measured between metastases within an animal. This sequence could be used to obtain diffusion information at high magnetic field.     

The Nlrp3 inflammasome,IL‐1β, and neutrophil recruitment are required for susceptibility to a nonhealing strain of Leishmania major in C57BL/6 mice

Infection of C57BL/6 mice with most Leishmania major strains results in a healing lesion and clearance of parasites from the skin. Infection of C57BL/6 mice with the L. major Seidman strain (LmSd), isolated from a patient with chronic lesions, despite eliciting a strong Th1 response, results in a nonhealing lesion, poor parasite clearance, and complete destruction of the ear dermis. We show here that in comparison to a healing strain, LmSd elicited early upregulation of IL‐1β mRNA and IL‐1β‐producing dermal cells and prominent neutrophil recruitment to the infected skin. Mice deficient in Nlrp3, apoptosis‐associated speck‐like protein containing a caspase recruitment domain, or caspase‐1/11, or lacking IL‐1β or IL‐1 receptor signaling, developed healing lesions and cleared LmSd from the infection site. Mice resistant to LmSd had a stronger antigen‐specific Th1 response. The possibility that IL‐1β might act through neutrophil recruitment to locally suppress immunity was supported by the healing observed in neutropenic Genista mice. Secretion of mature IL‐1β by LmSd‐infected macrophages in vitro was dependent on activation of the Nlrp3 inflammasome and caspase‐1. These data reveal that Nlrp3 inflammasome‐dependent IL‐1β, associated with localized neutrophil recruitment, plays a crucial role in the development of a nonhealing form of cutaneous leishmaniasis in conventionally resistant mice.     

Psychophysiological arousal and inter‐ and intraindividual differences in risk‐sensitive decision making

The current study assessed peripheral responses during decision making under explicit risk, and tested whether intraindividual variability in choice behavior can be explained by fluctuations in peripheral arousal. Electrodermal activity (EDA) and heart rate (HR) were monitored in healthy volunteers (N = 68) during the Roulette Betting Task. In this task, participants were presented with risky gambles to bet on, with the chances of winning varying across trials. Hierarchical Bayesian analyses demonstrated that EDA and HR acceleration responses during the decision phase were sensitive to the chances of winning. Interindividual differences in this peripheral reactivity during risky decision making were related to trait sensitivity to punishment and trait sensitivity to reward. Moreover, trial‐by‐trial variation in EDA and HR acceleration responses predicted a small portion of intraindividual variability in betting choices. Our results show that psychophysiological responses are sensitive to explicit risk and can help explain intraindividual heterogeneity in choice behavior.     

Harnessing T cells to fight cancer with BiTE® antibody constructs – past developments and future directions

Bispecific T-cell engager (BiTE^®) antibody constructs represent a novel immunotherapy that bridges cytotoxic T cells to tumor cells, thereby inducing target cell-dependent polyclonal T-cell activation and proliferation, and leading to apoptosis of bound tumor cells. Anti-CD19 BiTE^® blinatumomab has demonstrated clinical activity in Philadelphia chromosome (Ph)-negative relapsed or refractory (r/r) acute lymphoblastic leukemia (ALL) eventually resulting in conditional approval by the U.S. Food and Drug Administration in 2014. This drug is currently further developed in pediatric and Ph⁺ r/r, as well as in minimal residual disease-positive ALL, and might also offer clinical benefit for patients with non-Hodgkin's lymphoma, especially for those with aggressive forms like diffuse large B-cell lymphoma. Another BiTE^® antibody construct in hemato-oncology designated AMG 330 targets CD33 on acute myeloid leukemia blast cells. After showing promising ex vivo activity, this drug candidate has recently entered phase 1 clinical development, and has further indicated potential for combination with checkpoint inhibitors. In solid tumor indications, three BiTE^® antibody constructs have been tested in phase 1 studies so far: anti-EpCAM BiTE^® AMG 110, anti-CEA BiTE^® MEDI-565/AMG 211, and anti-PSMA BiTE^® BAY2010112/AMG 212. Pertinent questions comprise how to maximize BiTE^® penetration and T-cell infiltration of the tumor while simultaneously minimizing any adverse events, which is currently explored by a continuous intravenous infusion approach. Thus, BiTE^® antibody constructs will hopefully provide new treatment options for patients in several indications with high unmet medical need.