Management and Outcomes of Adults Diagnosed with Acute Pulmonary Embolism in Primary Care: Community-Based Retrospective Cohort Study.

BACKGROUND: The management and outcomes of patients diagnosed with acute pulmonary embolism in primary care have not been characterized. OBJECTIVE: To describe 30-day outcomes stratified by initial site-of-care decisions DESIGN: Multicenter retrospective cohort study PARTICIPANTS: Adults diagnosed with acute pulmonary embolism in primary care in a large, diverse community-based US health system (2013-2019) MAIN MEASURES: The primary outcome was a composite of 30-day serious adverse events (recurrent venous thromboembolism, major bleeding, and all-cause mortality). The secondary outcome was 7-day pulmonary embolism-related hospitalization, either initial or delayed. KEY RESULTS: Among 652 patient encounters (from 646 patients), median age was 64 years; 51.5% were male and 70.7% identified as non-Hispanic white. Overall, 134 cases (20.6%) were sent home from primary care and 518 cases (79.4%) were initially referred to the emergency department (ED) or hospital. Among the referred, 196 (37.8%) were discharged home from the ED without events. Eight patients (1.2%; 95% CI 0.5-2.4%) experienced a 30-day serious adverse event: 4 venous thromboemboli (0.6%), 1 major bleed (0.2%), and 3 deaths (0.5%). Seven of these patients were initially hospitalized, and 1 had been sent home from primary care. All 3 deaths occurred in patients with known metastatic cancer initially referred to the ED, hospitalized, then enrolled in hospice following discharge. Overall, 328 patients (50.3%) were hospitalized within 7 days: 322 at the time of the index diagnosis and 6 following initial outpatient management (4 clinic-only and 2 clinic-plus-ED patients). CONCLUSIONS: Patients diagnosed with acute pulmonary embolism in this primary care setting uncommonly experienced 30-day adverse events, regardless of initial site-of-care decisions. Over 20% were managed comprehensively by primary care. Delayed 7-day pulmonary embolism-related hospitalization was rare among the 51% treated as outpatients. Primary care management of acute pulmonary embolism appears to be safe and could have implications for cost-effectiveness and patient care experience.

The developmental and genetic basis of 'clubfoot' in the peroneal muscular atrophy mutant mouse.

Genetic factors underlying the human limb abnormality congenital talipes equinovarus ('clubfoot') remain incompletely understood. The spontaneous autosomal recessive mouse 'peroneal muscular atrophy' mutant (PMA) is a faithful morphological model of human clubfoot. In PMA mice, the dorsal (peroneal) branches of the sciatic nerves are absent. In this study, the primary developmental defect was identified as a reduced growth of sciatic nerve lateral motor column (LMC) neurons leading to failure to project to dorsal (peroneal) lower limb muscle blocks. The pma mutation was mapped and a candidate gene encoding LIM-domain kinase 1 (Limk1) identified, which is upregulated in mutant lateral LMC motor neurons. Genetic and molecular analyses showed that the mutation acts in the EphA4-Limk1-Cfl1/cofilin-actin pathway to modulate growth cone extension/collapse. In the chicken, both experimental upregulation of Limk1 by electroporation and pharmacological inhibition of actin turnover led to defects in hindlimb spinal motor neuron growth and pathfinding, and mimicked the clubfoot phenotype. The data support a neuromuscular aetiology for clubfoot and provide a mechanistic framework to understand clubfoot in humans.

Objectively Measured Daily Physical Activity and Postural Changes as Related to Positive and Negative Affect Using Ambulatory Monitoring Assessments.

OBJECTIVE: The aim of the study was to determine whether objectively measured daily physical activity and posture of sitting, standing, and sit-to-stand transitions are associated with daily assessments of affect. METHODS: Participants (N = 51, 49% female) wore ActivPal accelerometers for 24 h/d for seven consecutive days. Time spent sitting, standing, and being physically active and sit-to-stand transitions were derived for each day. Participants also completed a mood inventory each evening. Multilevel models examined within- and between-person associations of daily physical activity with positive and negative affect, adjusting for age, sex, body mass index, education, and sleep duration. RESULTS: Within-person associations showed that a 1-hour increase in daily physical activity was associated with a decrease in negative affect over the same day (B = -0.11, 95% confidence interval [CI], -0.21 to -0.01). Between-person associations indicated a borderline significant association between higher average daily physical activity levels and higher positive affect (B = 1.85, 95% CI = -0.25 to 3.94). There were no between- or within-person associations between sitting, standing, and sit-to-stand transitions with affect. CONCLUSIONS: Promoting physical activity may be a potential intervention strategy to acutely suppress negative affective states.

Instruments for assessing readiness to commence suck feeds in preterm infants: effects on time to establish full oral feeding and duration of hospitalisation.

BACKGROUND: One of the most challenging milestones for preterm infants is the acquisition of safe and efficient feeding skills. The majority of healthy full term infants are born with skills to coordinate their suck, swallow and respiration. However, this is not the case for preterm infants who develop these skills gradually as they transition from tube feeding to suck feeds. For preterm infants the ability to engage in oral feeding behaviour is dependent on many factors. The complexity of factors influencing feeding readiness has led some researchers to investigate the use of an individualised assessment of an infant's abilities. A limited number of instruments that aim to indicate an individual infant's readiness to commence either breast or bottle feeding have been developed. OBJECTIVES: To determine the effects of using a feeding readiness instrument when compared to no instrument or another instrument on the outcomes of time to establish full oral feeding and duration of hospitalisations. SEARCH METHODS: We used the standard search strategy of the Cochrane Neonatal Review group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 1), MEDLINE via PubMed (1966 to 22 February 2016), EMBASE (1980 to 22 February 2016), and CINAHL (1982 to 22 February 2016). We also searched clinical trials' databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing a formal instrument to assess a preterm infant's readiness to commence suck feeds with either no instrument (usual practice) or another feeding readiness instrument. DATA COLLECTION AND ANALYSIS: The standard methods of Cochrane Neonatal were used. Two authors independently screened potential studies for inclusion. No studies were found that met our inclusion criteria. MAIN RESULTS: No studies met the inclusion criteria. AUTHORS' CONCLUSIONS: There is currently no evidence to inform clinical practice, with no studies meeting the inclusion criteria for this review. Research is needed in this area to establish an evidence base for the clinical utility of implementing the use of an instrument to assess feeding readiness in the preterm infant population.

An exploration of the alcohol policy environment in post-conflict countries.

AIMS: Populations in countries emerging from armed conflict may have elevated levels of harmful alcohol use due to risk factors such as trauma exposure, increased daily stressors, elevated levels of mental health disorders, urbanization, and weak alcohol control policies and institutions. This study explores the challenges and opportunities for strengthening alcohol control policies in post-conflict countries. METHODS: Exploratory qualitative approach: experts (from United Nations agencies, non-governmental organizations, academic institutions and independent consultants) selected on the basis of their experience were interviewed. Thematic analysis identified key emergent themes. RESULTS: Perceived challenges to addressing harmful alcohol use in post-conflict countries included: lack of priority and recognition among key actors; limited resources and capacity, including in policy enforcement; and the role of the alcohol industry. Perceived opportunities included: increasing recognition of the harmful health and social effects of alcohol globally; sharing information, experience, and expertise to more effectively strengthen alcohol control policies; and collecting better data to advocate and inform stronger alcohol policies. CONCLUSION: This exploratory study provides a starting point to better understand the alcohol policy environment in post-conflict settings but considerably more research is required.

A systematic review of the effectiveness of warming interventions for women undergoing cesarean section.

BACKGROUND: Women undergoing cesarean section are vulnerable to adverse effects associated with inadvertent perioperative hypothermia, but there has been a lack of synthesized evidence for temperature management in this population. This systematic review aimed to synthesize the best available evidence in relation to preventing hypothermia in mothers undergoing cesarean section surgery. METHODS: Randomized controlled trials meeting the inclusion criteria (adult patients of any ethnic background, with or without comorbidities, undergoing any mode of anesthesia for any type of cesarean section) were eligible for consideration. Active or passive warming interventions versus usual care or placebo, aiming to limit or manage core heat loss in women undergoing cesarean section were considered. The primary outcome was maternal core temperature. A comprehensive search with no language restrictions was undertaken of multiple databases from their inception until May 2012. Two independent reviewers using the standardized critical appraisal instrument for randomized controlled trials from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instruments (JBI-MASTARI) assessed retrieved papers for methodological quality and conducted data collection. Where possible, results were combined in a fixed effects meta-analysis using the Cochrane Collaboration Review Manager software. Due to heterogeneity for one outcome, random effects meta-analysis was also used. RESULTS: A combined total of 719 participants from 12 studies were included. Intravenous fluid warming was found to be effective at maintaining maternal temperature and preventing shivering. Warming devices, including forced air warming and under-body carbon polymer mattresses, were effective at preventing hypothermia. However, effectiveness increased if the devices were applied preoperatively. Preoperative warming devices reduced shivering and improved neonatal temperatures at birth. Intravenous fluid warming did not improve neonatal temperature, and the effectiveness of warming interventions on umbilical pH remains unclear. LINKING EVIDENCE TO ACTION: Intravenous fluid warming by any method improves maternal temperature and reduces shivering during and after cesarean section, as does preoperative body warming. Preoperative warming strategies should be utilized where possible. Preoperative or intraoperative warmed IV fluids should be standard practice. Warming strategies are less effective when intrathecal opioids are administered. Further research is needed to investigate interventions in emergency cesarean section surgery. Larger scale studies using standardized, clinically meaningful temperature measurement time points are required.

Serine/threonine protein kinase SGK1 in glucocorticoid-dependent transdifferentiation of pancreatic acinar cells to hepatocytes.

Elevated glucocorticoid levels result in the transdifferentiation of pancreatic acinar cells into hepatocytes through a process that requires a transient repression of WNT signalling upstream of the induction of C/EBP-ß. However, the mechanism by which glucocorticoid interacts with WNT signalling is unknown. A screen of microarray data showed that the serine/threonine protein kinase SGK1 (serum- and glucocorticoid-regulated kinase 1) was markedly induced in the model B-13 pancreatic rat acinar cell line after glucocorticoid treatment (which converts them into hepatocyte-like 'B-13/H' cells) and this was confirmed at the level of mRNA (notably an alternatively transcribed SGK1C form) and protein. Knockdown of SGK1 using an siRNA designed to target all variant transcripts inhibited glucocorticoid-dependent transdifferentiation, whereas overexpression of the human C isoform (and also the human SGK1F isoform, for which no orthologue in the rat has been identified) alone - but not the wild-type A form - inhibited distal WNT signalling Tcf/Lef transcription factor activity, and converted B-13 cells into B-13/H cells. These effects were lost when the kinase functions of SGK1C and SGK1F were mutated. Inhibition of SGK1 kinase activity also inhibited glucocorticoid-dependent transdifferentiation. Expression of SGK1C and SGK1F resulted in the appearance of phosphorylated ß-catenin, and recombinant SGK1 was shown to directly phosphorylate purified ß-catenin in vitro in an ATP-dependent reaction. These data therefore demonstrate a crucial role for SGK1 induction in B-13 cell transdifferentiation to B-13/H hepatocytes and suggest that direct phosphorylation of ß-catenin by SGK1C represents the mechanism of crosstalk between glucocorticoid and WNT signalling pathways.

Processive bidirectional motion of dynein-dynactin complexes in vitro.

Cytoplasmic dynein is the primary molecular motor responsible for transport of vesicles, organelles, proteins and RNA cargoes from the periphery of the cell towards the nucleus along the microtubule cytoskeleton of eukaryotic cells. Dynactin, a large multi-subunit activator of dynein, docks cargo to the motor and may enhance dynein processivity. Here, we show that individual fluorescently labelled dynein-dynactin complexes exhibit bidirectional and processive motility towards both the plus and minus ends of microtubules. The dependence of this activity on substrate ATP concentration, nucleotide analogues and inhibitors suggests that bidirectional motility is an active energy-transduction property of dynein-dynactin motor mechano-chemistry. The unique motility characteristics observed may reflect the flexibility of the dynein structure that leads to an enhanced ability to navigate around obstacles in the cell.

Glucocorticoid-dependent transdifferentiation of pancreatic progenitor cells into hepatocytes is dependent on transient suppression of WNT signalling.

Developmentally, the pancreas and liver are closely related and pathological conditions - including elevated glucocorticoid levels - result in the appearance of hepatocytes in the pancreas. The role of the WNT signalling pathway in this process has been examined in the model transdifferentiating pancreatic acinar AR42J-B-13 (B-13) cell. Glucocorticoid treatment resulted in a transient loss of constitutive WNT3a expression, phosphorylation and depletion of beta-catenin, loss of beta-catenin nuclear localisation, and significant reductions in T-cell factor/lymphoid enhancer factor (Tcf/Lef) transcriptional activity before overt changes in phenotype into hepatocyte-like (B-13/H) cells. A return to higher Tcf/Lef transcriptional activity correlated with the re-expression of WNT3a in B-13/H cells. beta-catenin knock down alone substituted for and enhanced glucocorticoid-dependent transdifferentiation. Overexpression of a mutant beta-catenin (pt-Xbeta-cat) protein that blocked glucocorticoid-dependent suppression of Tcf/Lef activity resulted in inhibition of transdifferentiation. A small-molecule activator of Tcf/Lef transcription factors blocked glucocorticoid-dependent effects, as observed with pt-Xbeta-cat expression. Quercetin - a Tcf/Lef inhibitor - did not promote transdifferentiation into B-13/H cells, but did potentiate glucocorticoid-mediated transdifferentiation. These data demonstrate that the transdifferentiation of B-13 cells into hepatocyte-like cells in response to glucocorticoid was dependent on the repression of constitutively active WNT signalling.

Interaction between hedgehog signalling and PAX6 dosage mediates maintenance and regeneration of the corneal epithelium.

PURPOSE: To investigate the roles of intracellular signaling elicited by Hedgehog (Hh) ligands in corneal maintenance and wound healing. METHODS: The expression of Hedgehog pathway components in the cornea was assayed by immunohistochemistry, western blot and reverse-transcription polymerase chain reaction (RT-PCR), in wild-type mice and mice that were heterozygous null for the gene encoding the transcription factor, paired box gene 6 (Pax6).  Corneal epithelial wound healing and cell migration assays were performed after pharmacological upregulation and downregulation of the hedgehog pathway.  Reporter mice, mosaic for expression of the gene encoding ß-galactosidase (LacZ), were crossed to Pax6(+/-) mice, mice heterozygous for the gene encoding GLI-Kruppel family member GLI3, and Pax6(+/-)Gli3(+/-) double heterozygotes, to assay patterns of cell migration and corneal epithelial organization in vivo. RESULTS: Corneal epithelial wound healing rates increased in response to application of Sonic hedgehog (Shh), but only in mice with wild-type Pax6 dosage.  Downregulation of Hedgehog signalling inhibited corneal epithelial cell proliferation.  Pax6(+/-) corneal epithelia showed increased proliferation in response to exogenous Shh, but not increased migration. Desert hedgehog (Dhh) was shown to be the major endogenous ligand, with Shh detectable only by RT-PCR and only after epithelial wounding. The activity of phosphatidylinositol-3-OH kinase-γ (PI3Kγ) was not required for the increased migration response in response to Shh.  Nuclear expression of the activator form of the transcription factor Gli3 (which mediates Hh signalling) was reduced in Pax6(+/-) corneal epithelia. Pax6(+/-)Gli3(+/-) double heterozygotes showed highly disrupted patterns of clonal arrangement of cells in the corneal epithelium. CONCLUSIONS: The data show key roles for endogenous Dhh signalling in maintenance and regeneration of the corneal epithelium, demonstrate an interaction between Pax6 and Hh signalling in the corneal epithelium, and show that failure of Hh signalling pathways is a feature of Pax6(+/-) corneal disease that cannot be remedied pharmacologically by addition of the ligands.

Instruments for assessing readiness to commence suck feeds in preterm infants: effects on time to establish full oral feeding and duration of hospitalisation.

BACKGROUND: One of the most challenging milestones for preterm infants is the acquisition of safe and efficient feeding skills. The majority of healthy full term infants are born with skills to coordinate their suck, swallow and respiration. However, this is not the case for preterm infants who develop these skills gradually as they transition from tube feeding to suck feeds. For preterm infants the ability to engage in oral feeding behaviour is dependent on many factors. The complexity of factors influencing feeding readiness has led some researchers to investigate the use of an individualised assessment of an infant's abilities. A limited number of instruments that aim to indicate an individual infant's readiness to commence either breast or bottle feeding have been developed. OBJECTIVES: To determine the effects of using a feeding readiness instrument when compared to no instrument or another instrument on the outcomes of time to establish full oral feeding and duration of hospitalisation. SEARCH METHODS: We used the standard methods of the Cochrane Neonatal Review Group, including a search of the Cochrane Central Register of Controlled Trials (The Cochrane Library 2010, Issue 2), MEDLINE via EBSCO (1966 to July 2010), EMBASE (1980 to July 2010), CINAHL via EBSCO (1982 to July 2010), Web of Science via EBSCO (1980 to July 2010) and Health Source (1980 to July 2010). Other sources such as cited references from retrieved articles and databases of clinical trials were also searched. We did not apply any language restriction. We updated this search in March 2012. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing a formal instrument to assess a preterm infant's readiness to commence suck feeds with either no instrument (usual practice) or another feeding readiness instrument. DATA COLLECTION AND ANALYSIS: The standard methods of the Cochrane Neonatal Review Group were used. Two authors independently screened potential studies for inclusion. No studies were found that met our inclusion criteria. MAIN RESULTS: No studies met the inclusion criteria. AUTHORS' CONCLUSIONS: There is currently no evidence to inform clinical practice, with no studies meeting the inclusion criteria for this review. Research is needed in this area to establish an evidence base for the clinical utility of implementing the use of an instrument to assess feeding readiness in the preterm infant population.

Local cooling for relieving pain from perineal trauma sustained during childbirth.

BACKGROUND: Perineal trauma is common during childbirth and may be painful. Contemporary maternity practice includes offering women numerous forms of pain relief, including the local application of cooling treatments. OBJECTIVES: To evaluate the effectiveness and side effects of localised cooling treatments compared with no treatment, other forms of cooling treatments and non-cooling treatments. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (10 January 2012), CINAHL (1982 to 10 January 2012), the Australian New Zealand Clinical Trials Register (10 January 2012) and contacted experts in the field. SELECTION CRITERIA: Published and unpublished randomised and quasi-randomised trials (RCTs) that compared localised cooling treatment applied to the perineum with no treatment or other treatments applied to relieve pain related to perineal trauma sustained during childbirth. DATA COLLECTION AND ANALYSIS: At least two review authors independently assessed trials for inclusion, assessed trial quality and extracted data. A sub-set of data were double checked for accuracy. Analyses were performed on an intention-to-treat basis where data allowed. We sought additional information from the authors of three trials. MAIN RESULTS: Ten published RCTs were included (involving 1825 women). Comparisons were local cooling treatments (ice packs, cold gel pads (with or without compression) or cold/iced baths) with no treatment, gel pads with compression, hamamelis water (witch hazel), pulsed electromagnetic energy (PET), hydrocortisone/pramoxine foam (Epifoam), oral paracetamol or warm baths. Ice packs provided improved pain relief 24 to 72 hours after birth compared with no treatment (risk ratio (RR) 0.61; 95% confidence interval (CI) 0.41 to 0.91; one study, n = 208). Women preferred the utility of the gel pads compared with ice packs or no treatment (RR 0.82; 95% CI 0.73, 0.92). Differences detected in a composite of perineal oedema and bruising and overall wound healing were noted in one small study, favouring cold gel pads (n = 37) over ice (n = 35, mean difference (MD) 0.63 on a scale of 0 to 15; 95% CI 0.20 to 1.06) or no treatment (n = 39, MD -2.10; 95% CI -3.80 to -0.40) three to 14 days after giving birth. Women reported more pain (RR 5.60; 95% CI 2.35 to 13.33; one study, 100 women) and used more additional analgesia (RR 4.00; 95% CI 1.44 to 11.13; one study, 100 women) following the application of ice packs compared with PET. AUTHORS' CONCLUSIONS: There is only limited evidence to support the effectiveness of local cooling treatments (ice packs, cold gel pads, cold/iced baths) applied to the perineum following childbirth to relieve pain.

Feasibility and ethics of using data from the Scottish newborn blood spot archive for research.

Background: Newborn heel prick blood spots are routinely used to screen for inborn errors of metabolism and life-limiting inherited disorders. The potential value of secondary data from newborn blood spot archives merits ethical consideration and assessment of feasibility for public benefit. Early life exposures and behaviours set health trajectories in childhood and later life. The newborn blood spot is potentially well placed to create an unbiased and cost-effective population-level retrospective birth cohort study. Scotland has retained newborn blood spots for all children born since 1965, around 3 million in total. However, a moratorium on research access is currently in place, pending public consultation. Methods: We conducted a Citizens' Jury as a first step to explore whether research use of newborn blood spots was in the public interest. We also assessed the feasibility and value of extracting research data from dried blood spots for predictive medicine. Results: Jurors delivered an agreed verdict that conditional research access to the newborn blood spots was in the public interest. The Chief Medical Officer for Scotland authorised restricted lifting of the current research moratorium to allow a feasibility study. Newborn blood spots from consented Generation Scotland volunteers were retrieved and their potential for both epidemiological and biological research demonstrated. Conclusions: Through the Citizens' Jury, we have begun to identify under what conditions, if any, should researchers in Scotland be granted access to the archive. Through the feasibility study, we have demonstrated the potential value of research access for health data science and predictive medicine.

Neuroligin 1 is dynamically exchanged at postsynaptic sites.

Neuroligins are postsynaptic cell adhesion molecules that associate with presynaptic neurexins. Both factors form a transsynaptic connection, mediate signaling across the synapse, specify synaptic functions, and play a role in synapse formation. Neuroligin dysfunction impairs synaptic transmission, disrupts neuronal networks, and is thought to participate in cognitive diseases. Here we report that chemical treatment designed to induce long-term potentiation or long-term depression (LTD) induces neuroligin 1/3 turnover, leading to either increased or decreased surface membrane protein levels, respectively. Despite its structural role at a crucial transsynaptic position, GFP-neuroligin 1 leaves synapses in hippocampal neurons over time with chemical LTD-induced neuroligin internalization depending on an intact microtubule cytoskeleton. Accordingly, neuroligin 1 and its binding partner postsynaptic density protein-95 (PSD-95) associate with components of the dynein motor complex and undergo retrograde cotransport with a dynein subunit. Transgenic depletion of dynein function in mice causes postsynaptic NLG1/3 and PSD-95 enrichment. In parallel, PSD lengths and spine head sizes are significantly increased, a phenotype similar to that observed upon transgenic overexpression of NLG1 (Dahlhaus et al., 2010). Moreover, application of a competitive PSD-95 peptide and neuroligin 1 C-terminal mutagenesis each specifically alter neuroligin 1 surface membrane expression and interfere with its internalization. Our data suggest the concept that synaptic plasticity regulates neuroligin turnover through active cytoskeleton transport.

Disrupted pancreatic exocrine differentiation and malabsorption in response to chronic elevated systemic glucocorticoid.

Glucocorticoids are antiinflammatory therapeutics that have potent effects on cell differentiation. The aim of this study was to establish whether systemic glucocorticoid exposure significantly affects pancreatic differentiation in vivo because hepatocyte-like cells have been documented to occur in the diseased rodent pancreas. Expression of hepatic markers was examined in pancreata from mice genetically modified to secrete elevated circulating endogenous glucocorticoid [Tg(Crh)]. Tg(Crh) mice with elevated glucocorticoid appeared cushingoid and by 21 weeks of age were obese, insulin-resistant, and had extensive areas of hepatic gene expression in exocrine tissue. Acinar cells from Tg(Crh) mice costained for both amylase and cyp2e1, suggesting direct acinar-hepatic transdifferentiation. Hepatic expression increased with age in the pancreas to such an extent that malabsorption and rapid weight loss occurred in a subset of aging mice; this effect was reversed by dietary porcine pancreatic enzyme supplementation. Indeed, pancreatic expression of hepatic markers was prevented by adrenalectomy, establishing a direct role for glucocorticoid. Elevated levels of circulating glucocorticoid therefore promote a transdifferentiation of adult exocrine pancreas into hepatocyte-like cells, and chronic exposure results in pancreatic malfunction. Glucocorticoids are thus capable of modulating the differentiation of terminally differentiated adult cells.

A motor neuron disease-associated mutation in p150Glued perturbs dynactin function and induces protein aggregation.

The microtubule motor cytoplasmic dynein and its activator dynactin drive vesicular transport and mitotic spindle organization. Dynactin is ubiquitously expressed in eukaryotes, but a G59S mutation in the p150Glued subunit of dynactin results in the specific degeneration of motor neurons. This mutation in the conserved cytoskeleton-associated protein, glycine-rich (CAP-Gly) domain lowers the affinity of p150Glued for microtubules and EB1. Cell lines from patients are morphologically normal but show delayed recovery after nocodazole treatment, consistent with a subtle disruption of dynein/dynactin function. The G59S mutation disrupts the folding of the CAP-Gly domain, resulting in aggregation of the p150Glued protein both in vitro and in vivo, which is accompanied by an increase in cell death in a motor neuron cell line. Overexpression of the chaperone Hsp70 inhibits aggregate formation and prevents cell death. These data support a model in which a point mutation in p150Glued causes both loss of dynein/dynactin function and gain of toxic function, which together lead to motor neuron cell death.

Central nervous system intravascular lymphoma leading to rapidly progressive dementia.

Intravascular lymphoma is an uncommon subtype of B-cell lymphoma with neoplastic cells limited to the lumen of small blood vessels. We report a case of a 52-year-old man who presented with constitutional symptoms and rapidly progressive dementia. He was found to have diffuse leptomeningeal and faint parenchymal enhancement on magnetic resonance imaging and was subsequently diagnosed with intravascular lymphoma following a brain biopsy. He responded remarkably well to systemic and intrathecal chemotherapy. The diagnosis and treatment of intravascular lymphoma have been guided by a few case reports and are largely based on expert opinion.

A switch in retrograde signaling from survival to stress in rapid-onset neurodegeneration.

Retrograde axonal transport of cellular signals driven by dynein is vital for neuronal survival. Mouse models with defects in the retrograde transport machinery, including the Loa mouse (point mutation in dynein) and the Tg(dynamitin) mouse (overexpression of dynamitin), exhibit mild neurodegenerative disease. Transport defects have also been observed in more rapidly progressive neurodegeneration, such as that observed in the SOD1(G93A) transgenic mouse model for familial amyotrophic lateral sclerosis (ALS). Here, we test the hypothesis that alterations in retrograde signaling lead to neurodegeneration. In vivo, in vitro, and live-cell imaging motility assays show misregulation of transport and inhibition of retrograde signaling in the SOD1(G93A) model. However, similar inhibition is also seen in the Loa and Tg(dynamitin) mouse models. Thus, slowing of retrograde signaling leads only to mild degeneration and cannot explain ALS etiology. To further pursue this question, we used a proteomics approach to investigate dynein-associated retrograde signaling. These data indicate a significant decrease in retrograde survival factors, including P-Trk (phospho-Trk) and P-Erk1/2, and an increase in retrograde stress factor signaling, including P-JNK (phosphorylated c-Jun N-terminal kinase), caspase-8, and p75(NTR) cleavage fragment in the SOD1(G93A) model; similar changes are not seen in the Loa mouse. Cocultures of motor neurons and glia expressing mutant SOD1 (mSOD1) in compartmentalized chambers indicate that inhibition of retrograde stress signaling is sufficient to block activation of cellular stress pathways and to rescue motor neurons from mSOD1-induced toxicity. Hence, a shift from survival-promoting to death-promoting retrograde signaling may be key to the rapid onset of neurodegeneration seen in ALS.

Lysosomal proliferation and distal degeneration in motor neurons expressing the G59S mutation in the p150Glued subunit of dynactin.

An increasing number of neurodegenerative diseases are being linked to mutations in genes encoding proteins required for axonal transport and intracellular trafficking. A mutation in p150(Glued), a component of the cytoplasmic dynein/dynactin microtubule motor complex, results in the human neurodegenerative disease distal spinal and bulbar muscular atrophy (dSBMA). We have developed a transgenic mouse model of dSBMA; these mice exhibit late-onset, slowly progressive muscle weakness but do not have a shortened lifespan, consistent with the human phenotype. Examination of motor neurons from the transgenic model reveals the proliferation of enlarged tertiary lysosomes and lipofuscin granules, indicating significant alterations in the cellular degradative pathway. In addition, we observe deficits in axonal caliber and neuromuscular junction (NMJ) integrity, indicating distal degeneration of motor neurons. However, sciatic nerve ligation studies reveal that inhibition of axonal transport is not evident in this model. Together, these data suggest that mutant p150(Glued) causes neurodegeneration in the absence of significant changes in axonal transport, and therefore other functions of dynein/dynactin, such as trafficking in the degradative pathway and stabilization of the NMJ are likely to be critical in maintaining the health of motor neurons.