Microglia-astrocyte crosstalk regulates synapse remodeling via Wnt signaling.

Astrocytes and microglia are emerging key regulators of activity-dependent synapse remodeling that engulf and remove synapses in response to changes in neural activity. Yet, the degree to which these cells communicate to coordinate this process remains an open question. Here, we use whisker removal in postnatal mice to induce activity-dependent synapse removal in the barrel cortex. We show that astrocytes do not engulf synapses in this paradigm. Instead, astrocytes reduce their contact with synapses prior to microglia-mediated synapse engulfment. We further show that reduced astrocyte-contact with synapses is dependent on microglial CX3CL1-CX3CR1 signaling and release of Wnts from microglia following whisker removal. These results demonstrate an activity-dependent mechanism by which microglia instruct astrocyte-synapse interactions, which then provides a permissive environment for microglia to remove synapses. We further show that this mechanism is critical to remodel synapses in a changing sensory environment and this signaling is upregulated in several disease contexts.

MicroRNA governs bistable cell differentiation and lineage segregation via a noncanonical feedback.

Positive feedback driven by transcriptional regulation has long been considered a key mechanism underlying cell lineage segregation during embryogenesis. Using the developing spinal cord as a paradigm, we found that canonical, transcription-driven feedback cannot explain robust lineage segregation of motor neuron subtypes marked by two cardinal factors, Hoxa5 and Hoxc8. We propose a feedback mechanism involving elementary microRNA-mRNA reaction circuits that differ from known feedback loop-like structures. Strikingly, we show that a wide range of biologically plausible post-transcriptional regulatory parameters are sufficient to generate bistable switches, a hallmark of positive feedback. Through mathematical analysis, we explain intuitively the hidden source of this feedback. Using embryonic stem cell differentiation and mouse genetics, we corroborate that microRNA-mRNA circuits govern tissue boundaries and hysteresis upon motor neuron differentiation with respect to transient morphogen signals. Our findings reveal a previously underappreciated feedback mechanism that may have widespread functions in cell fate decisions and tissue patterning.

Experiences with making difficult decisions of the family caregivers of patients on prolonged mechanical ventilation: a qualitative study.

BACKGROUND: Family caregivers of patients on prolonged mechanical ventilation (PMV) may encounter challenges concerning medical decision-making besides witnessing patient suffering. Palliative care (PC) should be a good support for both patients and caregivers; however, for PMV families, PC is not always a choice through long companion time. This qualitative study clarifies family caregivers' burden of assisting patients on PMV and evaluates the need for PC information and support. METHODS: Interviews were caregivers of patients on ventilator support for more than 60 days in five hospitals of the Taipei City Hospital System. Based on phenomenology, this study was conducted by using a semistructured questionnaire comprising three questions: (I) what was the most crucial moment of deciding to intubate? (II) how would you describe the quality of life of your ventilator-dependent family member? (III) what type of assistance do you expect from the PC team for your ventilator-dependent family member? RESULTS: Twenty-one caregivers of patients on PMV in five hospitals of the Taipei City Hospital System agreed to participate in face-to-face interviews. The identified themes, including stressful decision-making, companion pain/discomfort, and unwillingness to accept PC, elucidated the difficulties experienced by caregivers when providing care. CONCLUSIONS: Understanding family caregivers' experiences can enable physicians to improve communication with them, encourage the PC team to support them during surrogate decision-making for patients on PMV during critical moments, and enhance the overall PC service.

Palliative medicine family conferences and caregiver psychological distress during prolonged mechanical ventilation.

OBJECTIVES: Little is known about the experience of family caregivers of patients who require prolonged mechanical ventilation (PMV). We examined the perspectives of caregivers of patients who died after PMV to explore the role of palliative care and the quality of dying and death (QODD) in patients and understand the psychological symptoms of these caregivers. METHODS: A longitudinal study was performed in five hospitals in Taipei, Taiwan. Routine palliative care family conferences and optional consultation with a palliative care specialist were provided, and family caregivers were asked to complete surveys. RESULTS: In total, 136 family caregivers of 136 patients receiving PMV were recruited and underwent face-to-face baseline interviews in 2016-2017. By 2018, 61 (45%) of 136 patients had died. We successfully interviewed 30 caregivers of patients' death to collect information on the QODD of patients and administer the Impact of Event Scale (IES), Hospital Anxiety and Depression Scale (HADS) and Center for Epidemiologic Studies Depression (CES-D) scale to caregivers. We observed that more frequent palliative care family conferences were associated with poorer QODD in patients (coefficients: -44.04% and 95% CIs -75.65 to -12.44), and more psychological symptoms among caregivers (coefficient: 9.77% and 95% CI 1.63 to 17.90 on CES-D and coefficient: 7.67% and 95% CI 0.78 to 14.55 on HADS). A higher caregiver burden at baseline correlated with lower psychological symptoms (coefficient: -0.35% and 95% CI -0.58 to -0.11 on IES and coefficient: -0.22% and 95% CI -0.40 to -0.05 on CES-D) among caregivers following the patients' death. Caregivers' who accepted the concept of palliative care had fewer psychological symptoms after patients' death (coefficient: -3.29% and 95% CI -6.32 to -0.25 on IES and coefficient: -3.22% and 95% CI -5.24 to -1.20 on CES-D). CONCLUSIONS: Palliative care conferences were more common among family members with increased distress. Higher caregiver burden and caregiver acceptance of palliative care at baseline both predicted lower levels of caregiver distress after death.

A comparably high virulence strain of porcine reproductive and respiratory syndrome virus isolated in Taiwan.

Porcine reproductive and respiratory syndrome virus (PRRSV) has been endemic in Taiwan since 1991. This study aimed to present a highly virulent PRRSV in Taiwan based on farm data collection and both in vitro and in vivo evaluations in virus challenge studies. This virulent PRRSV strain was first noticed on Farm TSYM due to continuously high nursery mortality rate and severe PRRSV-associated pneumonia. In phylogenetic surveillance, the PRRSV TSYM-strain remained in the predominant position for years, even with several other PRRSV strain invasions. In laboratory challenge trials, the TSYM-strain led to prolonged pyrexia, growth retardation, high mortality rates and high viremia titer that similar to the highly pathogenic PRRSV. The TSYM-strain isolate also triggered early interleukin-10 up-regulation and significantly higher infection rates under in vitro experiments. This study provides information of a comparably virulent strain in Taiwan and its appearance in both farm and laboratory levels.