Dopamine precursor depletion improves punishment prediction during reversal learning in healthy females but not males

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3D Microstructured Carbon Nanotube Electrodes for Trapping and Recording Electrogenic Cells

Electrogenic cells such as cardiomyocytes and neurons rely mainly on electrical signals for intercellular communication. Microelectrode arrays (MEAs) have been developed for long-term recording of cell signals and stimulation of electrogenic cells under low-cell-stress conditions, providing new insights in the behavior of electrogenic cells and the operation of the brain. To date, MEAs are relying on flat or needle-shaped electrode surfaces, mainly due to limitations in the lithographic processes. This paper relies on a previously reported elasto-capillary aggregation process to create 3D carbon nanotube (CNT) MEAs. This study shows that CNTs aggregate in well-shaped structures of similar size as cardiomyocytes are particularly interesting for MEA applications. This is because i) CNT microwells of the right diameter preferentially trap individual cardiomyocytes, which facilitates single cell recording without the need for clamping cells or signal deconvolution, and ii) once the cells are trapped inside of the CNT wells, this 3D CNT structure is used as an electrode surrounding the cell, which increases the cell-electrode contact area. As a result, this study finds that the recorded output voltages increase significantly (more than 200%). This fabrication process paves the way for future study of complex interactions between electrogenic cells and 3D recording electrodes.This work was supported by the Research Foundation—Flanders (FWO, Belgium) under Project No. 11S1214N. Michael De Volder was supported by the ERC Starting Grant (337739)—HIENA and the Marie Curie Grant CANA (618250). Davor Copic was supported by the Marie Curie Grant EmuCam (660351)

Disentangling the Roles of Approach, Activation and Valence in Instrumental and Pavlovian Responding

Hard-wired, Pavlovian, responses elicited by predictions of rewards and punishments exert significant benevolent and malevolent influences over instrumentally-appropriate actions. These influences come in two main groups, defined along anatomical, pharmacological, behavioural and functional lines. Investigations of the influences have so far concentrated on the groups as a whole; here we take the critical step of looking inside each group, using a detailed reinforcement learning model to distinguish effects to do with value, specific actions, and general activation or inhibition. We show a high degree of sophistication in Pavlovian influences, with appetitive Pavlovian stimuli specifically promoting approach and inhibiting withdrawal, and aversive Pavlovian stimuli promoting withdrawal and inhibiting approach. These influences account for differences in the instrumental performance of approach and withdrawal behaviours. Finally, although losses are as informative as gains, we find that subjects neglect losses in their instrumental learning. Our findings argue for a view of the Pavlovian system as a constraint or prior, facilitating learning by alleviating computational costs that come with increased flexibility

Hevin is down-regulated in many cancers and is a negative regulator of cell growth and proliferation

We have cloned a human Hevin cDNA from omental adipose tissue of different patients by reverse transcription polymerase chain reaction and shown a sequence variation due to a possible polymorphism at amino acid position 161 (E/G). Hevin protein expressed in vitro showed molecular weights of approximately 75 kDa and 150 kDa, suggesting that Hevin may form a homodimer in vitro. Using Northern blots and a human expressed sequence tAg database analysis, Hevin was shown to be widely expressed in human normal or non-neoplastic diseased tissues with various levels. In contrast to this, its expression was strongly down-regulated in most neoplastic cells or tissues tested. However, neither the mechanism nor the physiological meaning of this down-regulation is known. As an initial step towards investigating the functional role of Hevin in cell growth and differentiation, we transiently or stably expressed this gene in cancer cells (HeLa 3S) that are devoid of endogenous Hevin and measured DNA synthesis (cell proliferation) by 5-bromo-2′-deoxyuridine incorporation. Hevin was shown to be a negative regulator of cell proliferation. Furthermore, we have shown that Hevin can inhibit progression of cells from G1 to S phase or prolong G1 phase. This is the first report which describes the function of Hevin in cell growth and proliferation. Through database analysis, Hevin was found to be located on chromosome 4 which contains loss of heterozygosity of many tumour suppressor genes. Taken together, these results suggest that Hevin may be a candidate for a tumour suppressor gene and a potential target for cancer diagnosis/therapy. © 2000 Cancer Research Campaig

Human Substantia Nigra Neurons Encode Unexpected Financial Rewards

The brain's sensitivity to unexpected outcomes plays a fundamental role in an organism's ability to adapt and learn new behaviors. Emerging research suggests that midbrain dopaminergic neurons encode these unexpected outcomes. We used microelectrode recordings during deep brain stimulation surgery to study neuronal activity in the human substantia nigra (SN) while patients with Parkinson's disease engaged in a probabilistic learning task motivated by virtual financial rewards. Based on a model of the participants' expected reward, we divided trial outcomes into expected and unexpected gains and losses. SN neurons exhibited significantly higher firing rates after unexpected gains than unexpected losses. No such differences were observed after expected gains and losses. This result provides critical support for the hypothesized role of the SN in human reinforcement learning

A Study of the PDGF Signaling Pathway with PRISM

In this paper, we apply the probabilistic model checker PRISM to the analysis of a biological system -- the Platelet-Derived Growth Factor (PDGF) signaling pathway, demonstrating in detail how this pathway can be analyzed in PRISM. We show that quantitative verification can yield a better understanding of the PDGF signaling pathway.Comment: In Proceedings CompMod 2011, arXiv:1109.104

FIP1L1-PDGFRA molecular analysis in the differential diagnosis of eosinophilia

<p>Abstract</p> <p>Background</p> <p>Primary eosinophlia associated with the <it>FIP1L1-PDGFRA </it>rearrangement represents a subset of chronic eosinophilic leukaemia (CEL) and affected patients are very sensitive to imatinib treatment. This study was undertaken in order to examine the prevalence and the associated clinicopathologic and genetic features of <it>FIP1L1-PDGFRA </it>rearrangement in a cohort of 15 adult patients presenting with profound eosinophilia (> 1.5 × 10⁹/L).</p> <p>Methods</p> <p>Reverse transcriptase-polymerase chain reaction (RT-PCR) was used for the detection of <it>FIP1L1-PDGFRA </it>rearrangement and the results confirmed by direct sequencing. <it>C-KIT</it>-D816V mutation was analysed retrospectively by PCR and restriction-fragment-length-polymorphism (PCR-RFLP), in all cases with primary eosinophilia.</p> <p>Results</p> <p>Two male patients with splenomegaly carried the <it>FIP1L1-PDGFRA </it>rearrangement, whilst 2 others were ultimately classified as suffering from idiopathic hypereosinophlic syndrome (HES) and one from systemic mastocytosis. These patients were negative for the <it>C-KIT</it>-D816V mutation and received imatinib (100–400 mg daily). Patients with CEL and HES responded to imatinib and remained in complete haematological, clinical and molecular (for carriers of <it>FIP1L1-PDGFRA </it>rearrangement) remission for a median of 28.2 months (range: 11–54), whilst the patient with systemic mastocytosis did not respond. Interestingly, in both patients with <it>FIP1L1-PDGFRA </it>rearrangement, the breakpoints into <it>PDGFRA </it>were located within exon 12 and fused with exons 8 and 8a of <it>FIP1L1</it>, respectively.</p> <p>Conclusion</p> <p>An early diagnosis of <it>FIPIL1-PDGFRA</it>-positive CEL and imatinib treatment offer to the affected patients an excellent clinical therapeutic result, avoiding undesirable morbidity. Moreover, although the molecular mechanisms underlying disease pathogenesis remain to be determined, imatinib can be effective in patients with idiopathic HES.</p

Evidence for position effects as a variant ETV6-mediated leukemogenic mechanism in myeloid leukemias with a t(4;12)(q11-q12;p13) or t(5;12)(q31;p13)

The ETV6 gene (first identified as TEL) is a frequent target of chromosomal translocations in both myeloid and lymphoid leukemias. At present, more than 40 distinct translocations have been cytogenetically described, of which 13 have now also been characterized at the molecular level. These studies revealed the generation of in-frame fusion genes between different domains of ETV6 and partner genes encoding either kinases or transcription factors. However, in a number of cases-including a t(6;12)(q23;p13), the recurrent t(5;12)(q31;p13), and some cases of the t(4;12)(q11-q12;p13) described in this work-functionally significant fusions could not be identified, raising the question as to what leukemogenic mechanism is implicated in these cases. To investigate this, we have evaluated the genomic regions at 4q11-q12 and 5q31, telomeric to the breakpoints of the t(4;12)(q11-q12;p13) and t(5;12)(q31;p13). The homeobox gene GSH2 at 4q11-q12 and the IL-3/CSF2 locus at 5q31 were found to be located close to the respective breakpoints. In addition, GSH2 and IL-3 were found to be ectopically expressed in the leukemic cells, suggesting that expression of GSH2 and IL-3 was deregulated by the translocation. Our results indicate that, besides the generation of fusion transcripts, deregulation of the expression of oncogenes could be a variant leukemogenic mechanism for translocations involving the 5' end of ETV6, especially for those translocations lacking functionally significant fusion transcripts