Systematic Review of Motor Function Scales and Patient-Reported Outcomes in Spinal Muscular Atrophy.

ABSTRACT: Spinal muscular atrophy is a heterogeneous disease that results in loss of motor function. In an evolving treatment landscape, establishing the suitability and limitations of existing motor function scales and patient-reported outcomes used to monitor patients with this disease is important. A systematic review was conducted to examine utility of motor function scales and patient-reported outcomes in evaluating patients with spinal muscular atrophy. Published literature was reviewed up to June 2021 with no start date restriction. Of the reports screened, 122 were deemed appropriate for inclusion and are discussed in this review (including 24 validation studies for motor function scales or patient-reported outcomes). Fifteen motor function scales and patient-reported outcomes were identified to be commonly used (≥5 studies), of which 11 had available validation assessments. Each instrument has its strengths and limitations. It is imperative that the patient population (e.g., age, mobility), goals of treatment, and outcomes or endpoints of interest be considered when selecting the appropriate motor function scales and patient-reported outcomes for clinical studies.

Mortality Risk Profiles for Sepsis: A Novel Longitudinal and Multivariable Approach.

To determine if a set of time-varying biological indicators can be used to: 1) predict the sepsis mortality risk over time and 2) generate mortality risk profiles. DESIGN: Prospective observational study. SETTING: Nine Canadian ICUs. SUBJECTS: Three-hundred fifty-six septic patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Clinical data and plasma levels of biomarkers were collected longitudinally. We used a complementary log-log model to account for the daily mortality risk of each patient until death in ICU/hospital, discharge, or 28 days after admission. The model, which is a versatile version of the Cox model for gaining longitudinal insights, created a composite indicator (the daily hazard of dying) from the "day 1" and "change" variables of six time-varying biological indicators (cell-free DNA, protein C, platelet count, creatinine, Glasgow Coma Scale score, and lactate) and a set of contextual variables (age, presence of chronic lung disease or previous brain injury, and duration of stay), achieving a high predictive power (conventional area under the curve, 0.90; 95% CI, 0.86-0.94). Including change variables avoided misleading inferences about the effects of day 1 variables, signifying the importance of the longitudinal approach. We then generated mortality risk profiles that highlight the relative contributions among the time-varying biological indicators to overall mortality risk. The tool was validated in 28 nonseptic patients from the same ICUs who became septic later and was subject to 10-fold cross-validation, achieving similarly high area under the curve. CONCLUSIONS: Using a novel version of the Cox model, we created a prognostic tool for septic patients that yields not only a predicted probability of dying but also a mortality risk profile that reveals how six time-varying biological indicators differentially and longitudinally account for the patient's overall daily mortality risk.

The impact of the endothelial protein C receptor on thrombin generation and clot lysis.

INTRODUCTION: When thrombin is bound to thrombomodulin (TM), it becomes a potent activator of protein C (PC) and thrombin-activable fibrinolysis inhibitor (TAFI). Activation of PC is enhanced when PC is bound to the endothelial protein C receptor (EPCR). Activated protein C (APC) inhibits thrombin generation while activated TAFI (TAFIa) attenuates fibrinolysis. To determine the impact of diminished EPCR function on thrombin generation and fibrinolysis we generated cells that expressed TM and a variant of EPCR (R96C) that does not bind PC. METHODS: To determine the impact of EPCR on the generation of APC and TAFIa and how this affects thrombin generation and fibrinolysis we performed thrombin generation and clot lysis assays in the presence of cells expressing wild-type TM and EPCR (WT cells) or wild-type TM and the R96C variant of EPCR (R96C cells). RESULTS: In the presence of R96C cells, thrombin generation in normal plasma is increased, as a result of impaired PC activation when compared to WT cells. In addition, clot lysis is delayed in normal plasma in the presence of R96C cells, despite no increase in TAFI activation. In PC deficient plasma, clot lysis is delayed in the presence of WT and R96C cells as a result of increased TAFI activation. CONCLUSIONS: We demonstrate that impaired EPCR function can be detected by thrombin generation and clot lysis assays on cells expressing TM and EPCR. We also demonstrated that deficiency in EPCR has procoagulant effects that lead to a delay in clot lysis.

Phosphatidylserine externalization and procoagulant activation of erythrocytes induced by Pseudomonas aeruginosa virulence factor pyocyanin.

The opportunistic pathogen Pseudomonas aeruginosa causes a wide range of infections in multiple hosts by releasing an arsenal of virulence factors such as pyocyanin. Despite numerous reports on the pleiotropic cellular targets of pyocyanin toxicity in vivo, its impact on erythrocytes remains elusive. Erythrocytes undergo an apoptosis-like cell death called eryptosis which is characterized by cell shrinkage and phosphatidylserine (PS) externalization; this process confers a procoagulant phenotype on erythrocytes as well as fosters their phagocytosis and subsequent clearance from the circulation. Herein, we demonstrate that P. aeruginosa pyocyanin-elicited PS exposure and cell shrinkage in erythrocyte while preserving the membrane integrity. Mechanistically, exposure of erythrocytes to pyocyanin showed increased cytosolic Ca(2+) activity as well as Ca(2+) -dependent proteolytic processing of µ-calpain. Pyocyanin further up-regulated erythrocyte ceramide abundance and triggered the production of reactive oxygen species. Pyocyanin-induced increased PS externalization in erythrocytes translated into enhanced prothrombin activation and fibrin generation in plasma. As judged by carboxyfluorescein succinimidyl-ester labelling, pyocyanin-treated erythrocytes were cleared faster from the murine circulation as compared to untreated erythrocytes. Furthermore, erythrocytes incubated in plasma from patients with P. aeruginosa sepsis showed increased PS exposure as compared to erythrocytes incubated in plasma from healthy donors. In conclusion, the present study discloses the eryptosis-inducing effect of the virulence factor pyocyanin, thereby shedding light on a potentially important mechanism in the systemic complications of P. aeruginosa infection.

Characterization of mice harboring a variant of EPCR with impaired ability to bind protein C: novel role of EPCR in hematopoiesis.

The interaction of protein C (PC) with the endothelial PC receptor (EPCR) enhances activated PC (APC) generation. The physiological importance of EPCR has been demonstrated in EPCR knockout mice which show early embryonic lethality due to placental thrombosis. In order to study the role of EPCR independent of PC interaction, we generated an EPCR point mutation knock-in mouse (EPCR(R84A/R84A)) which lacks the ability to bind PC/APC. EPCR(R84A/R84A) mice are viable and reproduce normally. In response to thrombotic challenge with factor Xa/phospholipids, EPCR(R84A/R84A) mice generate more thrombin, less APC, and show increased fibrin deposition in lungs and heart compared with wild-type (WT) mice. EPCR(R84A/R84A) mice challenged with lipopolysaccharide generate less APC, more interleukin-6, and show increased neutrophil infiltration in the lungs compared with WT controls. Interestingly, EPCR(R84A/R84A) mice develop splenomegaly as a result of bone marrow (BM) failure. BM transplant experiments suggest a role for EPCR on hematopoietic stem cells and BM stromal cells in modulating hematopoiesis. Taken together, our studies suggest that impaired EPCR/PC-binding interactions not only result in procoagulant and proinflammatory effects, but also impact hematopoiesis.

Alpha-1 proteinase inhibitor M358R reduces thrombin generation when displayed on the surface of cells expressing tissue factor.

The M358R variant of alpha-1-proteinase inhibitor (API) is a potent soluble inhibitor of thrombin. Previously we engineered AR-API M358R, a membrane-bound form of this protein and showed that it inhibited exogenous thrombin when expressed on transfected cells lacking tissue factor (TF). To determine the suitability of AR-API M358R for gene transfer to vascular cells to limit thrombogenicity, we tested the ability of AR-API M358R to inhibit endogenous thrombin generated in plasma via co-expression co-expressing it on the surface of cells expressing TF. Transfected AR-API M358R formed inhibitory complexes with thrombin following exposure of recalcified, defibrinated plasma to TF on T24/83 cells, but discontinuously monitored thrombin generation was unaffected. Similarly, AR-API M358R expression did not reduce continuously monitored thrombin generation by T24/83 cell suspensions exposed to recalcified normal plasma in a Thrombogram-Thrombinoscope-type thrombin generation assay (TGA); in contrast, 1 µM hirudin variant 3 or soluble API M358R abolished thrombin generation. Gene transfer of TF to HEK 293 conferred the ability to support TF-dependent thrombin generation on HEK 293 cells. Co-transfection of HEK 293 cells with a 9:1 excess of DNA encoding AR-API M358R to that encoding TF reduced peak thrombin generation approximately 3-fold compared to controls. These in vitro results suggest that surface display of API M358R inhibits thrombin generation when the tethered serpin is expressed in excess of TF, and suggest its potential to limit thrombosis in appropriate vascular beds in animal models.

Targeted gene sequencing identifies variants in the protein C and endothelial protein C receptor genes in patients with unprovoked venous thromboembolism.

OBJECTIVE: The interaction of protein C (PC) with the endothelial PC receptor (EPCR) enhances activated PC generation. We performed targeted gene sequencing of the PC gene (PROC) and EPCR genes (PROCR) in patients with unprovoked venous thromboembolism (VTE) to determine whether mutations that impair PC-EPCR interactions are associated with an increased risk of VTE. APPROACH AND RESULTS: We sequenced exon 3 of PROC and exons 2 and 3 of PROCR (the exons that encode the protein-protein binding domains of PC and EPCR) in 653 patients with unprovoked VTE and in 627 healthy controls. Five single nucleotide variants, each in individual patients, were identified that result in abnormal PC (Arg9Cys, Val34Met, and Arg-1Cys) or abnormal EPCR proteins (Arg96Cys and Val170Leu). We did not detect any nonsynonymous coding variants in the controls. When the PC variants were expressed in human embryonic kidney 293 cells, all exhibited decreased synthesis, and 2 of the variants had reduced capacity for activated PC generation. When expressed on the surface of human embryonic kidney 293 cells, the EPCR variants showed reduced affinity for fluorescently labeled PC. In addition, the previously reported EPCR A3 haplotype, which promotes cellular shedding of EPCR, is over-represented in the patient group (P=0.001). CONCLUSIONS: This is the first targeted DNA sequencing analysis of PROC and PROCR in a large group of patients with unprovoked VTE. Our data suggest that mutations that impair PC-EPCR interactions may be associated with an increased risk of VTE.

Protective effects of activated protein C in sepsis.

Sepsis remains a complex syndrome associated with significant morbidity and mortality. It is now widely accepted that the pathways of inflammation, coagulation, apoptosis, and endothelial permeability are intimately linked in sepsis pathophysiology. The clinical success of activated protein C (APC), a natural anticoagulant, in reducing mortality in patients with severe sepsis has fuelled basic and preclinical research on the protective effects of this molecule. Over the past 15 years, impressive research advances have provided novel insights into the multifunctional activities of APC. APC is now viewed not only as an anticoagulant, but also as a cell signaling molecule that dampens the excessive or insufficiently controlled host response during sepsis. This review attempts to summarize the pleiotropic activities of APC with focus on its ability to inhibit coagulation, inflammation, apoptosis, and endothelial barrier breakdown. A comprehensive PUBMED literature review up to May 2008 was conducted.