In vitro modeling of dysfunctional glial cells in neurodegenerative diseases using human pluripotent stem cells

Most neurodegenerative diseases are characterized by a complex and mostly still unresolved pathology. This fact, together with the lack of reliable models, have precluded the development of effective therapies counteracting the disease progression. In the past few years, several studies have evidenced that lack of proper functionality of glial cells (astrocytes, microglia and oligodendrocytes) has a key role in the pathology of several neurodegenerative conditions including Alzheimer´s disease, amyotrophic lateral sclerosis and multiple sclerosis among others. However, this glial dysfunction is poorly modelled by available animal models, and we hypothesize that patientderived cells can serve as a better platform where to study this glial dysfunction. In this sense, human pluripotent stem cells (hPSCs) has revolutionized the field allowing the generation of disease-relevant neural cell types that can be used for disease modelling, drug screening and, possibly, cell transplantation purposes. In the case of the generation of oligodendrocytes (OLs) from hPSCs, we have developed a fast and robust protocol to generate surface antigen O4-positive (O4+) and myelin basic protein-positive OLs from hPSCs in only 22 days, including from patients with multiple sclerosis or amyotrophic lateral sclerosis. The generated cells resemble primary human OLs at the transcriptome level and can myelinate neurons in vivo. Using in vitro OLneuron co-cultures, effective myelination of neurons can also be demonstrated. This platform is being translated as well to the generation of the other glial cell types, allowing the derivation of patient-specific glial cells where to model disease-specific dysfunction. This methodology can be used for elucidating pathogenic pathways associated with neurodegeneration and to identify therapeutic targets susceptible of drug modulation, contributing to the development of novel and effective drugs for these devastating disorders.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Supported by PI18/01557 (to AG) and P18/1556 (to JV) grants from ISCiii of Spain co-financed by FEDER funds from European Union, and PI-0276-2018 grant (to JAGL) from Consejeria de Salud of Junta de Andalucia. JAGL held a postdoctoral contract from the I Research Plan Propio of the University of Malaga. CV and KE were supported by IWT-SBO-150031-iPSCAF and the Thierry Lathran Foundation grant – ALS-OL, and KN by FWO1166518

Using a gamified monitoring app to change adolescents' snack intake : the development of the REWARD app and evaluation design

Background: As the snacking pattern of European adolescents is of great concern, effective interventions are necessary. Till now health promotion efforts in children and adolescents have had only limited success in changing adolescents' eating patterns and anthropometrics. Therefore, the present study proposes an innovative approach to influence dietary behaviors in youth based on new insights on effective behavior change strategies and attractive intervention channels to engage adolescents. This article describes the rationale, the development, and evaluation design of the 'Snack Track School' app. The aim of the app is to improve the snacking patterns of Flemish 14- to 16-year olds. Methods: The development of the app was informed by the systematic, stepwise, iterative, and collaborative principles of the Intervention Mapping protocol. A four week mHealth intervention was developed based on the dual-system model with behavioral change strategies targeting both the reflective (i.e., active learning, advance organizers, mere exposure, goal-setting, monitoring, and feedback) and automatic processes (i.e., rewards and positive reinforcement). This intervention will be evaluated via a controlled pre-post design in Flemish schools among 1400 adolescents. Discussion: When this intervention including strategies focused on both the reflective and automatic pathway proves to be effective, it will offer a new scientifically-based vision, guidelines and practical tools for public health and health promotion (i.e., incorporation of learning theories in intervention programs)

Isolated limb perfusion with actinomycin D and TNF-alpha results in improved tumour response in soft-tissue sarcoma-bearing rats but is accompanied by severe local toxicity

Previously we demonstrated that addition of Tumour Necrosis Factor-α to melphalan or doxorubicin in a so-called isolated limb perfusion results in synergistic antitumour responses of sarcomas in both animal models and patients. Yet, 20 to 30% of the treated tumours do not respond. Therefore agents that synergise with tumour necrosis factor alpha must be investigated. Actinomycin D is used in combination with melphalan in isolated limb perfusion in the treatment of patients with melanoma in-transit metastases and is well known to augment tumour cell sensitivity towards tumour necrosis factor alpha in vitro. Both agents are very toxic, which limits their systemic use. Their applicability may therefore be tested in the isolated limb perfusion setting, by which the tumours can be exposed to high concentrations in the absence of systemic exposure. To study the beneficial effect of the combination in vivo, BN-175 soft tissue sarcoma-bearing rats were perfused with various concentrations of actinomycin D and tumour necrosis factor alpha. When used alone the drugs had only little effect on the tumour. Only when actinomycin D and tumour necrosis factor alpha were combined a tumour response was achieved. However, these responses were accompanied by severe, dose limiting, local toxicity such as destruction of the muscle tissue and massive oedema. Our results show that isolated limb perfusion with actinomycin D in combination with tumour necrosis factor alpha leads to a synergistic anti-tumour response but also to idiosyncratic locoregional toxicity to the normal tissues. Actinomycin D, in combination with tumour necrosis factor alpha, should not be explored in the clinical setting because of this. The standard approach in the clinic remains isolated limb perfusion with tumour necrosis factor alpha in combination with melphalan

Hydrological and climatological change associated with glacial recession in the Rwenzori Mountains of Uganda

The areal extent of tropical icefields in the Rwenzori Mountains of East Africa has reduced steadily over the last century from 7.5 km^{2} 2 in 1906 to <1 km^{2} in 2003. Considerable debate persists regarding the impact of deglaciation on alpine riverflow and changes in climate driving glacial recession in the East African Highlands. Recent field surveys combined with historical observations reveal continued, rapid retreat in the terminal positions of valley glaciers (Speke, Elena). Observed acceleration in the rate of termini retreat since the 1960s is shown to arise, in part, from the morphologies of the glaciers and the beds within which those glaciers reside. Historical data combined with the first measurements of alpine riverflow in the Rwenzori Mountains show that the contribution of meltwater flows from dwindling icefields to alpine riverflow is negligible, contributing <0.5% of the mean annual river discharge recorded at the base of the mountains. Preliminary high-frequency monitoring of air temperature and humidity in the vicinity of icefields on the Rwenzori Mountains indicates that elevated daily maximum air temperatures coincide with episodic reductions in relative humidity and increased meltwater fluxes observed during the dry season. A sustained reduction in humidity to account for observed deglaciation is not evident from records of lowland precipitation, humidity or river discharge. Lakelevel records in East Africa are also inconsistent with a sudden decrease in regional humidity around 1880AD that is proposed to have triggered deglaciation in the East African Highlands. Water levels in the lakes proximate to the icefields of Mount Kenya and Kilimanjaro are rising in the late 19th century when glaciers on these mountains are observed to be in retreat. Lake levels do not, furthermore, indicate that enhanced humidity over the 19th century prior to 1880AD relative to the 20th century. Evidence of warming over the latter half of the 20th century and an earlier onset of deglaciation (~1870AD) from meteorological and palaeolimnological data suggest that the timing and drivers of deglaciation in the Rwenzori Mountains are consistent with the recession of alpine icefields elsewhere in the tropics

Comparison of LFP-Based and Spike-Based Spectro-Temporal Receptive Fields and Cross-Correlation in Cat Primary Auditory Cortex

Multi-electrode array recordings of spike and local field potential (LFP) activity were made from primary auditory cortex of 12 normal hearing, ketamine-anesthetized cats. We evaluated 259 spectro-temporal receptive fields (STRFs) and 492 frequency-tuning curves (FTCs) based on LFPs and spikes simultaneously recorded on the same electrode. We compared their characteristic frequency (CF) gradients and their cross-correlation distances. The CF gradient for spike-based FTCs was about twice that for 2–40 Hz-filtered LFP-based FTCs, indicating greatly reduced frequency selectivity for LFPs. We also present comparisons for LFPs band-pass filtered between 4–8 Hz, 8–16 Hz and 16–40 Hz, with spike-based STRFs, on the basis of their marginal frequency distributions. We find on average a significantly larger correlation between the spike based marginal frequency distributions and those based on the 16–40 Hz filtered LFP, compared to those based on the 4–8 Hz, 8–16 Hz and 2–40 Hz filtered LFP. This suggests greater frequency specificity for the 16–40 Hz LFPs compared to those of lower frequency content. For spontaneous LFP and spike activity we evaluated 1373 pair correlations for pairs with >200 spikes in 900 s per electrode. Peak correlation-coefficient space constants were similar for the 2–40 Hz filtered LFP (5.5 mm) and the 16–40 Hz LFP (7.4 mm), whereas for spike-pair correlations it was about half that, at 3.2 mm. Comparing spike-pairs with 2–40 Hz (and 16–40 Hz) LFP-pair correlations showed that about 16% (9%) of the variance in the spike-pair correlations could be explained from LFP-pair correlations recorded on the same electrodes within the same electrode array. This larger correlation distance combined with the reduced CF gradient and much broader frequency selectivity suggests that LFPs are not a substitute for spike activity in primary auditory cortex

Independent Set Reconfiguration in Cographs

We study the following independent set reconfiguration problem, called TAR-Reachability: given two independent sets $I$ and $J$ of a graph $G$, both of size at least $k$, is it possible to transform $I$ into $J$ by adding and removing vertices one-by-one, while maintaining an independent set of size at least $k$ throughout? This problem is known to be PSPACE-hard in general. For the case that $G$ is a cograph (i.e. $P_4$-free graph) on $n$ vertices, we show that it can be solved in time $O(n^2)$, and that the length of a shortest reconfiguration sequence from $I$ to $J$ is bounded by $4n-2k$, if such a sequence exists. More generally, we show that if $X$ is a graph class for which (i) TAR-Reachability can be solved efficiently, (ii) maximum independent sets can be computed efficiently, and which satisfies a certain additional property, then the problem can be solved efficiently for any graph that can be obtained from a collection of graphs in $X$ using disjoint union and complete join operations. Chordal graphs are given as an example of such a class $X$

Enhancement of electroporation facilitated immunogene therapy via T-reg depletion

Regulatory T cells (T-regs) can negatively impact tumor antigen-specific immune responses after infiltration into tumor tissue. However, depletion of T-regs can facilitate enhanced anti-tumor responses, thus augmenting the potential for immunotherapies. Here we focus on treating a highly aggressive form of cancer using a murine melanoma model with a poor prognosis. We utilize a combination of T-reg depletion and immunotherapy plasmid DNA delivered into the B16F10 melanoma tumor model via electroporation. Plasmids encoding murine granulocyte macrophage colony-stimulating factor and human B71 were transfected with electroporation into the tumor and transient elimination of T-regs was achieved with CD25-depleting antibodies (PC61). The combinational treatment effectively depleted T-regs compared to the untreated tumor and significantly reduced lung metastases. The combination treatment was not effective in increasing the survival, but only effective in suppression of metastases. These results indicate the potential for combining T-reg depletion with immunotherapy-based gene electrotransfer to decrease systemic metastasis and potentially enhance survival

Semantic learning in autonomously active recurrent neural networks

The human brain is autonomously active, being characterized by a self-sustained neural activity which would be present even in the absence of external sensory stimuli. Here we study the interrelation between the self-sustained activity in autonomously active recurrent neural nets and external sensory stimuli. There is no a priori semantical relation between the influx of external stimuli and the patterns generated internally by the autonomous and ongoing brain dynamics. The question then arises when and how are semantic correlations between internal and external dynamical processes learned and built up? We study this problem within the paradigm of transient state dynamics for the neural activity in recurrent neural nets, i.e. for an autonomous neural activity characterized by an infinite time-series of transiently stable attractor states. We propose that external stimuli will be relevant during the sensitive periods, {\it viz} the transition period between one transient state and the subsequent semi-stable attractor. A diffusive learning signal is generated unsupervised whenever the stimulus influences the internal dynamics qualitatively. For testing we have presented to the model system stimuli corresponding to the bars and stripes problem. We found that the system performs a non-linear independent component analysis on its own, being continuously and autonomously active. This emergent cognitive capability results here from a general principle for the neural dynamics, the competition between neural ensembles.Comment: Journal of Algorithms in Cognition, Informatics and Logic, special issue on `Perspectives and Challenges for Recurrent Neural Networks', in pres