Ups and downs of lysosomal pH: conflicting roles of LAMP proteins?

The acidic pH of lysosomes is critical for catabolism in eukaryotic cells and is altered in neurodegenerative disease including Alzheimer and Parkinson. Recent reports using Drosophila and mammalian cell culture systems have identified novel and, at first sight, conflicting roles for the lysosomal associated membrane proteins (LAMPs) in the regulation of the endolysosomal system.Abbreviation: AD: Alzheimer disease; LAMP: lysosomal associated membrane protein; LTR: LysoTracker; PD: Parkinson disease; TMEM175: transmembrane protein 175; V-ATPase: vacuolar-type H+-translocating ATPase.

Synaptic BMAL1 phosphorylation controls circadian hippocampal plasticity.

The time of day strongly influences adaptive behaviors like long-term memory, but the correlating synaptic and molecular mechanisms remain unclear. The circadian clock comprises a canonical transcription-translation feedback loop (TTFL) strictly dependent on the BMAL1 transcription factor. We report that BMAL1 rhythmically localizes to hippocampal synapses in a manner dependent on its phosphorylation at Ser42 [pBMAL1(S42)]. pBMAL1(S42) regulates the autophosphorylation of synaptic CaMKIIα and circadian rhythms of CaMKIIα-dependent molecular interactions and LTP but not global rest/activity behavior. Therefore, our results suggest a model in which repurposing of the clock protein BMAL1 to synapses locally gates the circadian timing of plasticity.

Circulating Microvesicles Are Elevated Acutely following Major Burns Injury and Associated with Clinical Severity.

Microvesicles are cell-derived signaling particles emerging as important mediators and biomarkers of systemic inflammation, but their production in severe burn injury patients has not been described. In this pilot investigation, we measured circulating microvesicle levels following severe burns, with severe sepsis patients as a comparator group. We hypothesized that levels of circulating vascular cell-derived microvesicles are elevated acutely following burns injury, mirroring clinical severity due to the early onset and prevalence of systemic inflammatory response syndrome (SIRS) in these patients. Blood samples were obtained from patients with moderate to severe thermal injury burns, with severe sepsis, and from healthy volunteers. Circulating microvesicles derived from total leukocytes, granulocytes, monocytes, and endothelial cells were quantified in plasma by flow cytometry. All circulating microvesicle subpopulations were elevated in burns patients on day of admission (day 0) compared to healthy volunteers (leukocyte-microvesicles: 3.5-fold, p = 0.005; granulocyte-microvesicles: 12.8-fold, p<0.0001; monocyte-microvesicles: 20.4-fold, p<0.0001; endothelial- microvesicles: 9.6-fold, p = 0.01), but decreased significantly by day 2. Microvesicle levels were increased with severe sepsis, but less consistently between patients. Leukocyte- and granulocyte-derived microvesicles on day 0 correlated with clinical assessment scores and were higher in burns ICU non-survivors compared to survivors (leukocyte MVs 4.6 fold, p = 0.002; granulocyte MVs 4.8 fold, p = 0.003). Mortality prediction analysis of area under receiver operating characteristic curve was 0.92 (p = 0.01) for total leukocyte microvesicles and 0.85 (p = 0.04) for granulocyte microvesicles. These findings demonstrate, for the first time, acute increases in circulating microvesicles following burns injury in patients and point to their potential role in propagation of sterile SIRS-related pathophysiology.

eLearning to facilitate the education and implementation of the Chelsea Critical Care Physical Assessment: a novel measure of function in critical illness.

OBJECTIVE: To evaluate the efficacy of eLearning in the widespread standardised teaching, distribution and implementation of the Chelsea Critical Care Physical Assessment (CPAx) tool-a validated tool to assess physical function in critically ill patients. DESIGN: Prospective educational study. An eLearning module was developed through a conceptual framework, using the four-stage technique for skills teaching to teach clinicians how to use the CPAx. Example and test video case studies of CPAx assessments were embedded within the module. The CPAx scores for the test case studies and demographic data were recorded in a secure area of the website. Data were analysed for inter-rater reliability using intraclass correlation coefficients (ICCs) to see if an eLearning educational package facilitated consistent use of the tool. A utility and content validity questionnaire was distributed after 1 year to eLearning module registrants (n=971). This was to evaluate uptake of the CPAx in clinical practice and content validity of the CPAx from the perspective of clinical users. SETTING: The module was distributed for use via professional forums (n=2) and direct contacts (n=95). PARTICIPANTS: Critical care clinicians. PRIMARY OUTCOME MEASURE: ICC of the test case studies. RESULTS: Between July and October 2014, 421 candidates from 15 countries registered for the eLearning module. The ICC for case one was 0.996 (95% CI 0.990 to 0.999; n=207). The ICC for case two was 0.988 (0.996 to 1.000; n=184). The CPAx has a strong total scale content validity index (s-CVI) of 0.94 and is well used. CONCLUSIONS: eLearning is a useful and reliable way of teaching psychomotor skills, such as the CPAx. The CPAx is a well-used measure with high content validity rated by clinicians.

The responsiveness of the Chelsea Critical Care Physical Assessment tool in measuring functional recovery in the burns critical care population: an observational study.

INTRODUCTION: Severe burn leads to a state of hypercatabolism, resulting in rapid muscle loss and long-term disability. As survival rates from severe burn are improving, early rehabilitation is essential to facilitate functional recovery. However, there is no way of measuring the degree of disability in the acute stages, and hence, no marker of functional recovery. This hampers both communication and research into interventions to improve functional outcomes. The Chelsea Critical Care Physical Assessment tool (CPAx) is a simple objective measure of function, designed and validated in the general Intensive Care Unit (ICU) cohort. The aim of this study was to test the responsiveness of the CPAx in the burns ICU (BICU) cohort and validate its use. METHODS: Observational study of 52 BICU patients admitted for over 48h. All patients were assessed on the CPAx retrospectively for pre-admission, and prospectively at ICU admission, ICU discharge (or final ICU assessment for non-survivors) and hospital discharge. Analysis of variance, post hoc between group differences in median CPAx score, and floor and ceiling effect (i.e. the percentage of patients scoring full marks (50), or zero) for the four time points were completed. Minimal clinically important difference (MCID) was estimated as half of the standard deviation of the CPAx score at ICU discharge. RESULTS: A total of 30 patients were included in the final analysis; mean age was 47.1 years (SD 21.2), 63.3% were male, with a median burn total body surface area (TBSA) of 30% (IQR 11.3-48.8). There was a significant difference in the analysis of variance in median CPAx scores at all four time points (p<.001). In survivors, the differences in CPAx scores post hoc were significant for all time points (p<.05), aside from ICU discharge and hospital discharge. The CPAx MCID for BICU patients was six. Twenty-three (86.7%) patients scored full marks or zero on the CPAx pre-admission. For survivors, no patients scored full marks or zero on the CPAx at ICU and hospital discharge. On ICU admission 66.7% (n=20) scored zero on the CPAx and no patients scored 50. CONCLUSIONS: The CPAx score appears to be able to detect improvements in physical function as patients recover from acute severe burn. It has a limited floor and ceiling effect in the acute setting and a change in CPAx score of 6 represents clinically important progress. Further work is required in a larger cohort.