2,230 research outputs found

    Digistain: a novel biomarker imaging platform for grading breast carcinoma using routinely processed paraffin sections

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    Objective: Digistain is a new technology platform that enables imaging and quantification of a newly conceived biomarker for grading breast carcinoma in routinely processed, unstained paraffin sections without the use of traditional stains or contrasting agents. By recording a unique optical signature to analyze the chemical make-up of a biopsy quantitatively, the technique is unaffected by the subjectivity of traditional grading. Within minutes of loading a slide it yields a highly reproducible and user independent numerical score reflecting the cellularity of the tumour and its nuclear: cytoplasmic ratio. We report here our findings using an objective technique to grade breast tumours using quantitative criteria. Method: H&E stained sections from excision biopsies of 105 cases of invasive breast carcinoma were reviewed and graded using the ElstonEllis grading system. Unstained sections from each case were loaded into the Digistain platform to yield a numerical score - the Digistain Index (DI). Results: The cases were grouped according to histological grading. Mean DIs was calculated for each grade (1,2 and 3) to be 0.56, 0.61, and 0.68 respectively with a maximum standard error of 0.02. The DI spread within each grade was less than that across the three grades, thus validating this index as a viable grading indicator within the context of this study. Conclusion: We believe the new Digistain approach provides for the first time a cost effective and quantitative measure of tumour grade. This can be developed to deliver an effective assessment of prognosis and recurrence risk beyond traditional qualitative measures based on H&E staining protocols

    Robustness and Enhancement of Neural Synchronization by Activity-Dependent Coupling

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    We study the synchronization of two model neurons coupled through a synapse having an activity-dependent strength. Our synapse follows the rules of Spike-Timing Dependent Plasticity (STDP). We show that this plasticity of the coupling between neurons produces enlarged frequency locking zones and results in synchronization that is more rapid and much more robust against noise than classical synchronization arising from connections with constant strength. We also present a simple discrete map model that demonstrates the generality of the phenomenon.Comment: 4 pages, accepted for publication in PR

    The development of an accreditation scheme for accredited exercise physiologists

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    Background: Accredited Exercise Physiologists provide exercise services for people living with chronic disease, disability or injury and are recognised in Australia as Accredited Exercise Physiologists (AEP) under a national certification system administered by Exercise and Sport Science Australia (ESSA). A major breakthrough occurred for the AEP in 2006 when the Australian Department of Health and Ageing approved the AEP to deliver clinical exercise services for people with chronic medical conditions under the taxpayer-funded national health scheme, Medicare Australia. Aims: In light of these developments, the authors recognised the need for new accreditation criteria, and our report summarises the work that we did on behalf of the profession and ESSA in restructuring the accreditation system. Methods and Outcomes: We first performed a background study that defined the scope of practice of the AEP and benchmarked the AEP against other allied health professions in Australia and Clinical Exercise Physiologists internationally. We then constructed a new set of accreditation criteria comprising sets of pathologyspecific knowledge and experiences, together with a set of generic standards including communication, professional behaviour and risk management. All participating Australian universities (18 out of 27 responded) and 29 practitioner experts were then invited to provide comment and input into the draft guidelines. There was strong support for the new system that was implemented nationally on 1 January 2008 and is now administered by ESSA. Conclusions: This work has stimulated an unprecedented level of activity in the Australian university sector in developing new curricula in clinical exercise science and practice, and is intended to lead to improved standards of clinical exercise practice.<br /

    Limits and dynamics of stochastic neuronal networks with random heterogeneous delays

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    Realistic networks display heterogeneous transmission delays. We analyze here the limits of large stochastic multi-populations networks with stochastic coupling and random interconnection delays. We show that depending on the nature of the delays distributions, a quenched or averaged propagation of chaos takes place in these networks, and that the network equations converge towards a delayed McKean-Vlasov equation with distributed delays. Our approach is mostly fitted to neuroscience applications. We instantiate in particular a classical neuronal model, the Wilson and Cowan system, and show that the obtained limit equations have Gaussian solutions whose mean and standard deviation satisfy a closed set of coupled delay differential equations in which the distribution of delays and the noise levels appear as parameters. This allows to uncover precisely the effects of noise, delays and coupling on the dynamics of such heterogeneous networks, in particular their role in the emergence of synchronized oscillations. We show in several examples that not only the averaged delay, but also the dispersion, govern the dynamics of such networks.Comment: Corrected misprint (useless stopping time) in proof of Lemma 1 and clarified a regularity hypothesis (remark 1

    Democratization in a passive dendritic tree : an analytical investigation

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    One way to achieve amplification of distal synaptic inputs on a dendritic tree is to scale the amplitude and/or duration of the synaptic conductance with its distance from the soma. This is an example of what is often referred to as “dendritic democracy”. Although well studied experimentally, to date this phenomenon has not been thoroughly explored from a mathematical perspective. In this paper we adopt a passive model of a dendritic tree with distributed excitatory synaptic conductances and analyze a number of key measures of democracy. In particular, via moment methods we derive laws for the transport, from synapse to soma, of strength, characteristic time, and dispersion. These laws lead immediately to synaptic scalings that overcome attenuation with distance. We follow this with a Neumann approximation of Green’s representation that readily produces the synaptic scaling that democratizes the peak somatic voltage response. Results are obtained for both idealized geometries and for the more realistic geometry of a rat CA1 pyramidal cell. For each measure of democratization we produce and contrast the synaptic scaling associated with treating the synapse as either a conductance change or a current injection. We find that our respective scalings agree up to a critical distance from the soma and we reveal how this critical distance decreases with decreasing branch radius

    CDK7 inhibitors as anticancer drugs

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    Cyclin-dependent kinase 7 (CDK7), along with cyclin H and MAT1, forms the CDK-activating complex (CAK), which directs progression through the cell cycle via T-loop phosphorylation of cell cycle CDKs. CAK is also a component of the general transcription factor, TFIIH. CDK7-mediated phosphorylation of RNA polymerase II (Pol II) at active gene promoters permits transcription. Cell cycle dysregulation is an established hallmark of cancer, and aberrant control of transcriptional processes, through diverse mechanisms, is also common in many cancers. Furthermore, CDK7 levels are elevated in a number of cancer types and are associated with clinical outcomes, suggestive of greater dependence on CDK7 activity, compared with normal tissues. These findings identify CDK7 as a cancer therapeutic target, and several recent publications report selective CDK7 inhibitors (CDK7i) with activity against diverse cancer types. Preclinical studies have shown that CDK7i cause cell cycle arrest, apoptosis and repression of transcription, particularly of super-enhancer-associated genes in cancer, and have demonstrated their potential for overcoming resistance to cancer treatments. Moreover, combinations of CDK7i with other targeted cancer therapies, including BET inhibitors, BCL2 inhibitors and hormone therapies, have shown efficacy in model systems. Four CDK7i, ICEC0942 (CT7001), SY-1365, SY-5609 and LY3405105, have now progressed to Phase I/II clinical trials. Here we describe the work that has led to the development of selective CDK7i, the current status of the most advanced clinical candidates, and discuss their potential importance as cancer therapeutics, both as monotherapies and in combination settings. ClinicalTrials.gov Identifiers: NCT03363893; NCT03134638; NCT04247126; NCT03770494

    Tamoxifen, aminoglutethimide and danazol: effect of therapy on hormones in post-menopausal patients with breast cancer.

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    Gonadotrophins, oestradiol, androstenedione, testosterone and dehydroepiandrosterone sulphate (DHAS) were measured sequentially in 72 patients with advanced breast cancer receiving endocrine therapy of various types. Tamoxifen significantly reduced gonadotrophins but did not effect other hormones. Danazol also reduced gonadotrophins. Aminoglutethimide (AGT) reduced oestradiol and DHAS but had not effect on gonadotrophins. The effects of administering tamoxifen, AGT and danazol together (TAD) together were therefore examined. This combination reduced gonadotrophins, oestradiol and DHAS, but no further than tamoxifen and AGT alone. The degree and duration of hormone suppression were similar in both responders and non-responders to tamoxifen, AGT or TAD, though patients responding to AGT showed more complete suppression at the end of the course of treatment, perhaps because they were treated longer. On relapse, adequate gonadotrophin and steroid suppression was demonstrated in patients receiving tamoxifen and AGT respectively. We conclude that (a) response to endocrine therapy is unlikely to be related to the degree of endocrine suppression produced by the therapy; (b) combination endocrine therapy does not further reduce serum-hormone concentrations and (c) relapse is unlikely to be due to escape from the hormone-inhibitory effects of endocrine agents
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