DHX9 Helicase promotes R-loop formation in cells with impaired RNA splicing

Unresolved R-loops can represent a threat to genome stability. Here the authors reveal that DHX9 helicase can promote R-loop formation in the absence of splicing factors SFPQ and SF3B3

Insulin Concentration Modulates Hepatic Lipid Accumulation in Mice in Part via Transcriptional Regulation of Fatty Acid Transport Proteins

Fatty liver disease (FLD) is commonly associated with insulin resistance and obesity, but interestingly it is also observed at low insulin states, such as prolonged fasting. Thus, we asked whether insulin is an independent modulator of hepatic lipid accumulation.In mice we induced, hypo- and hyperinsulinemia associated FLD by diet induced obesity and streptozotocin treatment, respectively. The mechanism of free fatty acid induced steatosis was studied in cell culture with mouse liver cells under different insulin concentrations, pharmacological phosphoinositol-3-kinase (PI3K) inhibition and siRNA targeted gene knock-down. We found with in vivo and in vitro models that lipid storage is increased, as expected, in both hypo- and hyperinsulinemic states, and that it is mediated by signaling through either insulin receptor substrate (IRS) 1 or 2. As previously reported, IRS-1 was up-regulated at high insulin concentrations, while IRS-2 was increased at low levels of insulin concentration. Relative increase in either of these insulin substrates, was associated with an increase in liver-specific fatty acid transport proteins (FATP) 2&5, and increased lipid storage. Furthermore, utilizing pharmacological PI3K inhibition we found that the IRS-PI3K pathway was necessary for lipogenesis, while FATP responses were mediated via IRS signaling. Data from additional siRNA experiments showed that knock-down of IRSs impacted FATP levels.States of perturbed insulin signaling (low-insulin or high-insulin) both lead to increased hepatic lipid storage via FATP and IRS signaling. These novel findings offer a common mechanism of FLD pathogenesis in states of both inadequate (prolonged fasting) and ineffective (obesity) insulin signaling

Modeling Brain Resonance Phenomena Using a Neural Mass Model

Stimulation with rhythmic light flicker (photic driving) plays an important role in the diagnosis of schizophrenia, mood disorder, migraine, and epilepsy. In particular, the adjustment of spontaneous brain rhythms to the stimulus frequency (entrainment) is used to assess the functional flexibility of the brain. We aim to gain deeper understanding of the mechanisms underlying this technique and to predict the effects of stimulus frequency and intensity. For this purpose, a modified Jansen and Rit neural mass model (NMM) of a cortical circuit is used. This mean field model has been designed to strike a balance between mathematical simplicity and biological plausibility. We reproduced the entrainment phenomenon observed in EEG during a photic driving experiment. More generally, we demonstrate that such a single area model can already yield very complex dynamics, including chaos, for biologically plausible parameter ranges. We chart the entire parameter space by means of characteristic Lyapunov spectra and Kaplan-Yorke dimension as well as time series and power spectra. Rhythmic and chaotic brain states were found virtually next to each other, such that small parameter changes can give rise to switching from one to another. Strikingly, this characteristic pattern of unpredictability generated by the model was matched to the experimental data with reasonable accuracy. These findings confirm that the NMM is a useful model of brain dynamics during photic driving. In this context, it can be used to study the mechanisms of, for example, perception and epileptic seizure generation. In particular, it enabled us to make predictions regarding the stimulus amplitude in further experiments for improving the entrainment effect

The Immune System in Stroke

Stroke represents an unresolved challenge for both developed and developing countries and has a huge socio-economic impact. Although considerable effort has been made to limit stroke incidence and improve outcome, strategies aimed at protecting injured neurons in the brain have all failed. This failure is likely to be due to both the incompleteness of modelling the disease and its causes in experimental research, and also the lack of understanding of how systemic mechanisms lead to an acute cerebrovascular event or contribute to outcome. Inflammation has been implicated in all forms of brain injury and it is now clear that immune mechanisms profoundly influence (and are responsible for the development of) risk and causation of stroke, and the outcome following the onset of cerebral ischemia. Until very recently, systemic inflammatory mechanisms, with respect to common comorbidities in stroke, have largely been ignored in experimental studies. The main aim is therefore to understand interactions between the immune system and brain injury in order to develop novel therapeutic approaches. Recent data from clinical and experimental research clearly show that systemic inflammatory diseases -such as atherosclerosis, obesity, diabetes or infection - similar to stress and advanced age, are associated with dysregulated immune responses which can profoundly contribute to cerebrovascular inflammation and injury in the central nervous system. In this review, we summarize recent advances in the field of inflammation and stroke, focusing on the challenges of translation between pre-clinical and clinical studies, and potential anti-inflammatory/immunomodulatory therapeutic approaches

The Spectrum of C9orf72-mediated Neurodegeneration and Amyotrophic Lateral Sclerosis

The discovery that a hexanucleotide repeat expansion in C9orf72 is the most numerous genetic variant of both amyotrophic lateral sclerosis and frontotemporal dementia has opened a rapidly growing field, which may provide long hoped for advances in the understanding and treatment of these devastating diseases. In this review we describe the various phenotypes, clinical and pathological, associated with expansion of C9orf72, which go beyond amyotrophic lateral sclerosis and frontotemporal dementia to include neurodegeneration more broadly. Next we take a step back and summarize the current understanding of the C9orf72 expansion and its protein products at a molecular level. Three mechanisms are prominent: toxicity mediated directly by RNA transcribed from the repeat; toxicity mediated by dipeptide repeat proteins translated from the repeat sequence; and haploinsufficiency resulting from reduced transcription of the C9orf72 exonic sequence. A series of exciting advances have recently described how dipeptide repeat proteins might interfere with the normal role of the nucleolus in maturation of RNA binding proteins and in production of ribosomes. Importantly, these mechanisms are unlikely to be mutually exclusive. We draw attention to the fact that clinical and pathological similarities to other genetic variants without a repeat expansion must not be overlooked in ascribing a pathogenic mechanism to C9orf72-disease. Finally, with a view to impact on patient care, we discuss current practice with respect to genetic screening in patients with and without a family history of disease, and the most promising developments towards therapy that have been reported to date

Cost-effectiveness of home-based care of febrile neutropenia in children with cancer.

INTRODUCTION: Home-based treatment of febrile neutropenia (FN) in children with cancer with oral or intravenous antibiotics is safe and effective. There are limited data on the economic impact of this model of care. We evaluated the cost-effectiveness of implementing an FN programme, incorporating home-based intravenous antibiotics for carefully selected patients, in a tertiary paediatric hospital. METHODS: A decision analytic model was constructed to compare costs and outcomes of the home-based FN programme, with usual in-hospital treatment with intravenous antibiotics. The programme included a clinical decision rule to stratify patients by risk for severe infection and home-based eligibility criteria using disease, chemotherapy and patient-level factors. Health outcomes (quality of life) and probabilities of FN risk classification and home-based eligibility were based on prospectively collected data between 2017 and 2019. Patient-level costs were extracted from hospital administrative records. Cost-effectiveness was expressed as the incremental cost per quality-adjusted life year (QALY). FINDINGS: The mean health care cost of home-based FN treatment in low-risk patients was Australian dollars (A$) 7765 per patient compared to A$20,396 for in-hospital treatment (mean difference A$12,632 [95% CI: 12,496-12,767]). Overall, the home-based FN programme was the dominant strategy, being more effective (0.0011 QALY [95% CI: 0.0011-0.0012]) and less costly. Results of the model were most sensitive to proportion of children eligible for home-based care programme. CONCLUSION: Compared to in-hospital FN care, the home-based FN programme is cost-effective, with savings arising from cheaper cost of caring for children at home. These savings could increase as more patients eligible for home-based care are included in the programme

Home-based care of low-risk febrile neutropenia in children-an implementation study in a tertiary paediatric hospital.

BackgroundHome-based management of low-risk febrile neutropenia (FN) is safe, improves quality of life and reduces healthcare expenditure. A formal low-risk paediatric program has not been implemented in Australia. We aimed to describe the implementation process and evaluate the clinical impact.MethodThis prospective study incorporated three phases: implementation, intervention and evaluation. A low-risk FN implementation toolkit was developed, including a care-pathway, patient information, home-based assessment and educational resources. The program had executive-level endorsement, a multidisciplinary committee and a nurse specialist. Children with cancer and low-risk FN were eligible to be transferred home with a nurse visiting daily after an overnight period of observation for intravenous antibiotics. Low-risk patients were identified using a validated decision rule, and suitability for home-based care was determined using disease, chemotherapy and patient-level criteria. Plan-Do-Study-Act methodology was used to evaluate clinical impact and safety.ResultsOver 18 months, 292 children with FN were screened: 132 (45%) were low-risk and 63 (22%) were transferred to home-based care. Compared with pre-implementation there was a significant reduction in in-hospital median LOS (4.0 to 1.5 days, p ConclusionThis program significantly reduces in-hospital LOS for children with low-risk FN. Ongoing evaluation will inform sustainability, identify areas for improvement and support national scale-up of the program