Correlation between different LDL-R mutations and response to ab-PCSK9 therapy in a group of patient with genetic diagnosis of Familial Hypercholesterolemia. Preliminary report

Introduction

Familial hypercholesterolemia (FH) is an autosomal dominant disease that leads to premature cardiovascular disease (CAD). The availability of ab-PCSK9 has changed the approach to therapy.

Purpose

To evaluate the relationship between different types of mutations in LDLR gene and response to ab-PCSK9.

Methods

73 FH patients, 33 women and 40 men (53.9±13. yrs), in primary prevention (N=46) and secondary prevention (N=27), were recruited. This sample included patients with mutations in LDLR gene: heterozygotes for missense mutations (N=31), for null mutations (N=31), compound heterozygotes or homozygotes (N=11). At baseline, the whole sample had a maximally tolerated lipid lowering therapy (MT-LLT) without ab-PCSK9; 16 patients had MT-LLTs intolerance. After 160 days with ab-PCSK9 therapy we evaluated the achievement of a goal (LDL-C<70 mg/dL in primary prevention without Diabetes Mellitus, LDL-C<55 mg/dL).

Results

After 160 days of therapy with ab-PCSK9 (45 patients on Alirocumab, 28 patients on Evolocumab) and MT-LLT, 29/73 patients (39.7%) of the whole sample achieve the goal of LDL-C. Of them 14/29 (48.2%) were in primary prevention, 15/29 (51.7%) in secondary prevention, no difference in achievement of the goal. We then evaluated the percent of patients achieving the goal of LDL-C:

15/31 (48.3%) patients with missense mutation and 14/31 (45.1%) patients with null mutation, no significant difference among groups;

0/11 compound heterozygotes or homozygotes;

3/16 (18.7%) MT-LLTs intolerance.

The other main cardiovascular risk factors did not influence of the achievement the goal of LDL cholesterol.

Conclusions

Lack of correlation between type of mutation in heterozygous FH patients and ab-PCSK9 therapy response; response was significantly poorest in patients with compound heterozygosis or homozygosis mutation as compared to heterozygotes; the intolerance to MT-LLT was significant in the achievement of the goal of LDL-C.

Different between guideline 2016 vs 2019

Funding Acknowledgement

Type of funding source: None

Random auxetics from buckling fibre networks

Auxetic materials have gained increasing interest in the last decades, fostered by auspicious applications in various fields. While the design of new auxetics has largely focused on meta-materials with deterministic, periodically arranged structures, we show here by theoretical and numerical analysis that pronounced auxetic behaviour with negative Poisson's ratios of very large magnitude can occur in random fibre networks with slender, reasonably straight fibre segments that buckle and deflect. We further demonstrate in experiments that such auxetic fibre networks, which increase their thickness by an order of magnitude and more than quintuple their volume when moderately extended, can be produced by electrospinning. Our results thus augment the class of auxetics by a large group of straightforwardly fabricable meta-materials with stochastic microstructure.

Correlating diameter, mechanical and structural properties of poly(l-lactide) fibres from needleless electrospinning

The development and application of nanofibres requires a thorough understanding of the mechanical properties on a single fibre level including respective modelling tools for precise fibre analysis. This work presents a mechanical and morphological study of poly-l-lactide nanofibres developed by needleless electrospinning. Atomic force microscopy (AFM) and micromechanical testing (MMT) were used to characterise the mechanical response of the fibres within a diameter range of 200-1400 nm. Young's moduli E determined by means of both methods are in sound agreement and show a strong increase for thinner fibres below a critical diameter of 800 nm. Similar increasing trends for yield stress and hardening modulus were measured by MMT. Finite element analyses show that the common practice of modelling three-point bending tests with either double supported or double clamped beams is prone to significant bias in the determined elastic properties, and that the latter is a good approximation only for small diameters. Therefore, an analytical formula based on intermediate boundary conditions is proposed that is valid for the whole tested range of fibre diameters, providing a consistently low error in axial Young's modulus below 10%. The analysis of fibre morphology by differential scanning calorimetry and 2D wide-angle X-ray scattering revealed increasing polymer chains alignment in the amorphous phase and higher crystallinity of fibres for decreasing diameter. The combination of these observations with the mechanical characterisation suggests a linear relationship between Young's modulus and both crystallinity and molecular orientation in the amorphous phase. STATEMENT OF SIGNIFICANCE: Fibrous membranes have rapidly growing use in various applications, each of which comes with specific property requirements. However, the development and production of nanofibre membranes with dedicated mechanical properties is challenging, in particular with techniques suitable for industrial scales such as needleless electrospinning. It is therefore a key step to understand the mechanical and structural characteristics of single nanofibres developed in this process, and to this end, the present work presents changes of internal fibre structure and mechanical properties with diameter, based on dedicated models. Special attention was given to the commonly used models for analyzing Young's modulus of single nanofibers in three-point bending tests, which are shown to be prone to large errors, and an improved robust approach is proposed.

Activation of Blood Coagulation after Abrupt or Stepwise Withdrawal of Oral Anticoagulants - A Prospective Study

The occurrence of a “rebound hypercoagulable state” in patients after discontinuation of oral anticoagulants is still a matter of debate and no definite recommendation can be made on the best procedure for anticoagulant withdrawal. The present study investigated the changes in the levels of markers of activated blood coagulation in 32 patients (pts) in whom warfarin treatment (for venous thromboembolic disease) was randomly withdrawn abruptly (n = 17, group A) or gradually (n = 15, group B: ⅔ of initial dose the 1st week, ⅓ the 2nd weeks and nothing from the 3rd week on). Blood was sampled at baseline, once a week for the first three weeks and after 2 months. At the 1st week group A had significantly higher F1+2 and TAT values (p <0.001); at the 2nd week F1 + 2 levels remained higher (p <0.05) though INR values were not different from those of group B. After baseline, higher than normal F1+2 levels were recorded in 32/66 (48%) controls in group A vs 15/60 (25%) in group B (p <0.01); at the 2nd week, 10/17 (59%) patients in group A vs 1/15 (7%) in group B still had higher than normal F1+2 levels (p <0.01 ). The values of areas under curve (AUC) and maximum concentrations of all variables were not statistically different in the two groups; however, very high levels were observed in a few cases of group A. Thrombotic events (one DVT recurrence and one thrombophlebitis in a varicose vein) occurred in 2 pts of group A, both with high F1+2 and TAT AUC values. In conclusion, the present study shows that withdrawal of oral anticoagulants elicits low grade transient clotting activation, which is more intense and longer lasting after abrupt discontinuation. In single cases, however, such activation is particularly intense. It is possible that these cases are at greater risk of thrombotic complications.

Stroke Simulation Improves Acute Stroke Management: A Systems-Based Practice Experience

BACKGROUND

Literature on the effectiveness of simulation-based medical education programs for caring for acute ischemic stroke (AIS) patients is limited.

OBJECTIVE

To improve coordination and door-to-needle (DTN) time for AIS care, we implemented a stroke simulation training program for neurology residents and nursing staff in a comprehensive stroke center.

METHODS

Acute stroke simulation training was implemented for first-year neurology residents in July 2011. Simulations were standardized using trained live actors, who portrayed stroke vignettes in the presence of a board-certified vascular neurologist. A debriefing of each resident's performance followed the training. The hospital stroke registry was also used for retrospective analysis. The study population was defined as all patients treated with intravenous tissue plasminogen activator for AIS between October 2008 and September 2014.

RESULTS

We identified 448 patients meeting inclusion criteria. Simulation training independently predicted reduction in DTN time by 9.64 minutes (95% confidence interval [CI] -15.28 to -4.01, P = .001) after controlling for age, night/day shift, work week versus weekend, and blood pressure at presentation (> 185/110). Systolic blood pressure higher than 185 was associated with a 14.28-minute increase in DTN time (95% CI 3.36-25.19, P = .011). Other covariates were not associated with any significant change in DTN time.

CONCLUSIONS

Integration of simulation based-medical education for AIS was associated with a 9.64-minute reduction in DTN time.

High Mortality among 30-Day Readmission after Stroke: Predictors and Etiologies of Readmission

BACKGROUND

Although some risk factors for stroke readmission have been reported, the mortality risk is unclear. We sought to evaluate etiologies and predictors of 30-day readmissions and determine the associated mortality risk.

METHODS

This is a retrospective case-control study evaluating 1,544 patients admitted for stroke (hemorrhagic, ischemic, or TIA) from January 2013 to December 2014. Of these, 134 patients readmitted within 30 days were identified as cases; 1,418 other patients, with no readmissions were identified as controls. Patients readmitted for hospice or elective surgery were excluded. An additional 248 patients deceased on index admission were included for only a comparison of mortality rates. Factors explored included socio-demographic characteristics, clinical comorbidities, stroke characteristics, and length of stay. Chi-square test of proportions and multivariable logistic regression were used to identify independent predictors of 30-day stroke readmissions. Mortality rates were compared for index admission and readmission and among readmission diagnoses.

RESULTS

Among the 1,544 patients in the main analysis, 67% of index stroke admissions were ischemic, 22% hemorrhagic, and 11% TIA. The 30-day readmission rate was 8.7%. The most common etiologies for readmission were infection (30%), recurrent stroke and TIA (20%), and cardiac complications (14%). Significantly higher proportion of those readmitted for recurrent strokes and TIAs presented within the first week (p = 0.039) and had a shorter index admission length of stay (p = 0.027). Risk factors for 30-day readmission included age >75 (p = 0.02), living in a facility prior to index stroke (p = 0.01), history of prior stroke (p = 0.03), diabetes (p = 0.03), chronic heart failure (p ≤ 0.001), atrial fibrillation (p = 0.03), index admission to non-neurology service (p < 0.01), and discharge to other than home (p < 0.01). On multivariate analysis, index admission to a non-neurology service was an independent predictor of 30-day readmission (p ≤ 0.01). The mortality after a within 30-day readmission after stroke was higher than index admission (36.6 vs. 13.8% p ≤ 0.001) (OR 3.6 95% CI 2.5-5.3). Among those readmitted, mortality was significantly higher for those admitted for a recurrent stroke (p = 0.006).

CONCLUSION

Approximately one-third of 30-day readmissions were infection related and one-fifth returned with recurrent stroke or TIA. Index admission to non-neurology service was an independent risk factor of 30-day readmissions. The mortality rate for 30-day readmission after stroke is more than 2.5 times greater than index admissions and highest among those readmitted for recurrent stroke. Identifying high-risk patients for readmission, ensuring appropriate level of service, and early outpatient follow-up may help reduce 30-day readmission and the high associated risk of mortality.

Electrospraying of microfluidic encapsulated cells for the fabrication of cell-laden electrospun hybrid tissue constructs

The fabrication of functional 3D tissues is a major goal in tissue engineering. While electrospinning is a promising technique to manufacture a structure mimicking the extracellular matrix, cell infiltration into electrospun scaffolds remains challenging. The robust and in situ delivery of cells into such biomimetic scaffolds would potentially enable the design of tissue engineered constructs with spatial control over cellular distribution but often solvents employed in the spinning process are problematic due to their high cytotoxicity. Herein, microfluidic cell encapsulation is used to establish a temporary protection vehicle for the in situ delivery of cells for the development of a fibrous, cell-laden hybrid biograft. Therefore a layer-by-layer process is used by alternating fiber electrospinning and cell spraying procedures. Both encapsulation and subsequent electrospraying of capsules has no negative effect on the viability and myogenic differentiation of murine myoblast cells. Propidium iodide positive stained cells were analyzed to quantify the amount of dead cells and the presence of myosin heavy chain positive cells after the processes was shown. Furthermore, encapsulation successfully protects cells from cytotoxic solvents (such as dimethylformamide) during in situ delivery of the cells into electrospun poly(vinylidene fluoride-co-hexafluoropropylene) scaffolds. The resulting cell-populated biografts demonstrate the clear potential of this approach in the creation of viable tissue engineering constructs.

STATEMENT OF SIGNIFICANCE

Infiltration of cells and their controlled spatial distribution within fibrous electrospun membranes is a challenging task but allows for the development of functional highly organized 3D hybrid tissues. Combining polymer electrospinning and cell electrospraying in a layer-by-layer approach is expected to overcome current limitations of reduced cell infiltration after traditional static seeding. However, organic solvents, used during the electrospinning process, impede often major issues due to their high cytotoxicity. Utilizing microfluidic encapsulation as a mean to embed cells within a protective polymer casing enables the controlled deposition of viable cells without interfering with the cellular phenotype. The presented techniques allow for novel cell manipulation approaches being significant for enhanced 3D tissue engineering based on its versatility in terms of material and cell selection.

A review of the application of reinforced hydrogels and silk as biomaterials for intervertebral disc repair

The degeneration of the intervertebral disc (IVD) within the spinal column represents a major pain source for many patients. Biological restoration or repair of the IVD using "compressive-force-resistant" and at the same time "cytocompatible" materials would be desirable over current purely mechanical solutions, such as spinal fusion or IVD implants. This review provides an overview of recent research on the repair of the inner (nucleus pulposus = NP) and the outer (annulus fibrous = AF) parts of the IVD tissue. Many studies have addressed NP repair using hydrogel-like materials. However, only a few studies have so far focused on AF repair. As the AF possesses an extremely low self-healing capacity and special attention to shear-force resistance is essential, special repair designs are required. In our review, we stated the challenges in IVD repair and highlighted the use of composite materials such as silk biomaterials and fibrin cross-linked reinforced hydrogels. We elaborated on the origin of silk and its many in tissue engineering. Furthermore, techniques such as electrospinning and 3D printing technologies allow the fabrication of versatile and functionalised 3D scaffolds. We summarised the research that has been conducted in the field of regenerative medicine over the recent years, with a special focus on the potential application and the potential of combining silk and reinforced - and thus mechanically tailored - hydrogels for IVD repair.

CCL11 (Eotaxin-1) Levels Predict Long-Term Functional Outcomes in Patients Following Ischemic Stroke

Circulating levels of the pro-inflammatory cytokine C-C motif chemokine 11 (CCL11, also known as eotaxin-1) are increased in several animal models of neuroinflammation, including traumatic brain injury and Alzheimer's disease. Increased levels of CCL11 have also been linked to decreased neurogenesis in mice. We hypothesized that circulating CCL11 levels would increase following ischemic stroke in mice and humans, and that higher CCL11 levels would correlate with poor long-term recovery in patients. As predicted, circulating levels of CCL11 in both young and aged mice increased significantly 24 h after experimental stroke. However, ischemic stroke patients showed decreased CCL11 levels compared to controls 24 h after stroke. Interestingly, lower post-stroke CCL11 levels were predictive of increased stroke severity and independently predictive of poorer functional outcomes in patients 12 months after ischemic stroke. These results illustrate important differences in the peripheral inflammatory response to ischemic stroke between mice and human patients. In addition, it suggests CCL11 as a candidate biomarker for the prediction of acute and long-term functional outcomes in ischemic stroke patients.

Abstract TP188: Migraine History is the Only Predictor of Negative Diffusion Weighted Imaging in Patients Treated with IV-Thrombolytic

Background: Migraine, seizures, and psychiatric disorders are frequently reported as “stroke mimics” in patients with negative diffusion weighted imaging (DWI) after IV-tPA. We sought to determine predictors of negative DWI in suspected stroke patients treated with IV-tPA.

Methods: A retrospective case-control study encompassing all acute stroke patients treated with IV-tPA (at our hospital or "dripped and shipped") from January 2013-December 2014 was conducted. A total of 275 patients were identified with 47 negative DWI cases and 228 positive DWI controls. Variables including demographic factors, stroke characteristics, and clinical comorbidities were analyzed for statistical significance. A multivariate logistic regression was performed (SPSS-24) to identify predictors of negative DWI.

Results: Approximately 17% of patients had negative DWI after IV-tPA. Compared to controls, migraine history independently predicted negative DWI (OR 5.0 95% CI 1.03-24.6, p=0.046). Increasing age (OR 0.97 95% CI 0.94-0.99, p=0.02) and atrial fibrillation (OR 0.25 95% CI 0.08-0.77 p=0.01) predicted lower probability of negative DWI. Gender, admission NIHSS, treatment location, pre-admission modified Rankin scale, diabetes mellitus, hypertension, hyperlipidemia, symptom side, seizure history, and psychiatric history did not predict negative DWI status.

Conclusion: In our study, only pre-existing migraine history independently predicted negative DWI after IV-tPA treatment in suspected stroke patients. Although helpful in acute evaluation, this should not preclude treatment with IV-tPA considering the outcomes of missed strokes and low complication risk of IV-tpa in these patients.

Abstract WMP87: Simulation Based Medical Education Improves Door to Needle Times in Acute Ischemic Stroke Management

Introduction: Literature on the effectiveness of simulation based medical education programs used in acute ischemic stroke (AIS) care is scant. In an effort to improve coordination and door to needle time (DNT) for AIS care, a stroke simulation education training program for neurology nursing staff and neurology residents was implemented in a comprehensive stroke center.

Methods: Hospital stroke registry was used for retrospective analysis. The study population was defined as all patients treated with IV-tPA for AIS in the emergency room from October 2008 to September 2014. Simulation training was implemented yearly, for a three month period starting from July 2011. All neurology residents and a group of nurses trained to respond to all AIS cases participated. Simulations were standardized, using deliberate practice with a trained live actor portraying stroke vignettes in the presence of a board certified vascular neurologist. During the period of study, there were no changes in Emergency Department stroke triage protocol, or changes in first provider response to AIS. The data was analyzed using IBM SPSS24 software.

Results: We identified 448 patients admitted with AIS who were treated with IV-tPA. The average DNT on univariate analysis before and after intervention was 67.9 and 58.3 minutes [p <0.001]. A multivariate linear regression analysis was performed controlling for age, night/day shift, weekday/weekend, and blood pressure at presentation (>185/110). After controlling for confounders we found that simulation training independently reduced the DNT by 9.64 minutes [95% confidence interval (CI) 4.01 - 15.28, p=0.001]. Amongst other co-variates, only the systolic blood pressure >185 was associated with 14.27 minutes of delay in DNT [95% CI 3.36 - 25.191, p=0.011].

Conclusion: Time to thrombolysis from symptom onset is a critical factor in AIS management and evidence shows improving the DNT could improve patient outcomes. In our six year study, integration of simulation based medical education for AIS reduced the average DNT by 9.64 minutes in multivariate analysis. Simulation based medical education therefore should be considered as a standard process for providers involved in the care of AIS patients receiving thrombolytic treatment.

Abstract TP282: High Mortality Among 30-Day Readmission After Stroke: Predictors and Etiologies of Readmission

Background: Although risk factors for readmission have been reported, the mortality risk is unclear. We sought to evaluate etiologies and predictors of 30-day readmission and determine the associated mortality risk.

Methods: This is a retrospective case-control study evaluating stroke patients (hemorrhagic, ischemic or TIA) from January 2013-December 2014 and those readmitted within 30 days after index event; including 135 readmitted patients and 1,664 controls. Readmission for hospice or elective surgery were excluded. Socio-demographics, clinical variables and potential risk factors were assessed using chi-square test of proportions and multi variable logistic regression was performed to identify independent predictors of 30-day stroke readmission. Index mortality was compared to readmission mortality and odds associated with readmission was identified.

Results: Overall, 67% of index stroke admissions were ischemic, 19% hemorrhagic, and 14% TIA. The 30-day readmission rate was 7.3%. The most common etiologies for readmission were infection (30%), recurrent stroke (17%), and cardiac complications (14%). Recurrent strokes presented earliest (p=0.047) and had a shorter index admission length of stay (p=0.02.) Risk factors for 30-day readmission included age > 75 ( p=0.04 ), lack of spouse ( p=0.05 ), living in a facility prior to index stroke ( p=0.033 ), history of prior stroke ( p=0.02 ), diabetes ( p=.018 ), CHF ( p=<.0001 ), atherosclerosis ( p=<0.01 ), admission to non-stroke unit ( p=0.02 ), non-home discharge status ( p<0.01 ), and index admission to a non-neurology service was an independent predictor of 30-day readmission (p=<0.01). The overall mortality associated with 30-day readmission after stroke was higher as compared to index admission (37.3% vs 13.3% p =<0.01) (OR 3.7 95%CI 2.5-5.3) and was not influenced by recurrent stroke (p=0.37) .

Conclusion: In our study, infection and recurrent stroke were most common causes and index admission to a non-neurology service was the strongest readmission predictor. The overall mortality is high and not influenced by recurrent stroke. Identifying high risk patients, ensuring appropriate level of service and early outpatient follow-up may help reduce 30-day readmission and risk of mortality.

Abstract WP54: Early MRI Facilitates Stroke Evaluation and Decreases Length of Stay for Ischemic Stroke Patients

Background: Imaging studies are an integral part of stroke evaluation and non-contrast head CT is the initial imaging modality. Although critical for assessing acute hemorrhage, ischemic changes may not be visible on CT for up to 24 hours. MRI brain detects ischemic changes within 20 minutes of symptom onset. It is an invaluable tool to confirm an ischemic stroke and determine its etiology. A focused workup for stroke etiology or evaluation for stroke mimics accelerates management strategies and reduces length of stay in the hospital. Early discharge facilitates early rehabilitation and better functional recovery of stroke patients. Current guidelines for management of acute stroke recommend head CT within 25 minutes of presentation. However, to date, a recommendation regarding timeline for MRI brain in stroke evaluation is lacking. Objective of this study was to investigate the correlation between time to MRI & length of hospital stay to functional outcome in stroke patients.

Methods: 648 patients (mean age 69±0.5 years; 50.4% women) admitted to Hartford Hospital (Comprehensive Stroke Center) with a focal neurological deficit in the year 2014 and got a CT head and MRI brain were enrolled in the study. Data collection was done via stroke database and retrospective chart review. Patients with any hemorrhage or age<18 years, were excluded from the study. We used Mann-Whitney U and Spearman’s correlation co-efficient to compare time from arrival to MRI and length of stay in the hospital.

Results: There was a significant effect of time from arrival to MRI on length of hospital stay (r=0.27, p<0.01). Subgroup analysis revealed a significant decrease in length of stay if MRI was done within 12 hours of admission (p<0.02) as compared to 24 hours or above (p<0.12). Based on MRI findings, 27% patients had a new diagnosis of stroke and in 24.1% patients stroke was ruled out. This change in diagnosis had a significant effect on length of stay (Z=-2.4, p<0.02).

Conclusions: Our study indicates that delay in MRI for a suspected stroke increases hospital length of stay. It suggests MRI within 12 hours of admission to be the new standard of care for stroke patients. Ongoing work will assess the correlation of timing to MRI to functional outcomes in stroke patients.

An easy synthetic way to exfoliate and stabilize MWCNTs in a thermoplastic pyrrole-containing matrix assisted by hydrogen bonds

MWCNTs were dispersed in a thermoplastic polymer containing pyrrole units in the main chain and hydroxyl pendant groups, affording a well-distributed percolative network. The resulting soft nanocomposite shows stable conductive behavior.

A forest of SiO2 nanowires covered by a TiO2 thin film for an efficient photocatalytic water treatment

Disordered TiO₂/SiO₂ nanowires possess enhanced photocatalytic activity due to the synergy of morphology and light trapping properties of the NW forest.

Functional characterization of mutant genes associated with autosomal dominant familial hypercholesterolemia: integration and evolution of genetic diagnosis

AIMS

Familial Hypercholesterolemia (FH) is one of the most frequent dyslipidemias, the autosomal dominant form of which is primarily caused by mutations in the LDL receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin type 9 (PCSK9) genes, although in around 20% of patients the genetic cause remains unidentified. Genetic testing has notably improved the identification of patients suffering from FH, the most frequent cause of which is the presence of mutations in the LDLR gene. Although more than 1200 different mutations have been identified in this gene, about 80% are recognized to be pathogenic. We aim to overview the current methods used to perform the functional characterization of mutations causing FH and to highlight the conditions requiring a functional characterization of the variant in order to obtain a diagnostic report.

DATA SYNTHESIS

In the current review, we summarize the different types of functional assays - including their advantages and disadvantages - performed to characterize mutations in the LDLR, APOB and PCSK9 genes helping to better define their pathogenic role. We describe the evaluation of splicing alterations and two major procedures for functional characterization: 1. ex vivo methods, using cells from FH patients; 2. in vitro methods using cell lines.

CONCLUSIONS

Functional characterization of the LDLR, APOB and PCSK9 mutant genes associated with FH can be considered a necessary integration of its genetic diagnosis.

Polyuria and cerebral vasospasm after aneurysmal subarachnoid hemorrhage

Background

Natriuresis with polyuria is common after aneurysmal subarachnoid hemorrhage (aSAH). Previous studies have shown an increased risk of symptomatic cerebral vasospasm or delayed cerebral ischemia (DCI) in patients with hyponatremia and/or the cerebral salt wasting syndrome (CSW). However, natriuresis may occur in the absence of hyponatremia or hypovolemia and it is not known whether the increase in DCI in patients with CSW is secondary to a concomitant hypovolemia or because the physiology that predisposes to natriuretic peptide release also predisposes to cerebral vasospasm. Therefore, we investigated whether polyuria per se was associated with vasospasm and whether a temporal relationship existed.

Methods

A retrospective review of patients with aSAH was performed. Exclusion criteria were admission more than 48 h after aneurysmal rupture, death within 5 days, and the development of diabetes insipidus or acute renal failure. Polyuria was defined as >6 liters of urine in a 24 h period. Vasospasm was defined as a mean velocity > 120 m/s on Transcranial Doppler Ultrasonography (TCDs) or by evidence of vasospasm on computerized tomography (CT) or catheter angiography. Multivariable logistic regression was performed to assess the relationship between polyuria and vasospasm.

Results

95 patients were included in the study. 51 had cerebral vasospasm and 63 met the definition of polyuria. Patients with polyuria were significantly more likely to have vasospasm (OR 4.301, 95 % CI 1.378–13.419) in multivariate analysis. Polyuria was more common in younger patients (52 vs 68, p <.001) but did not impact mortality after controlling for age and disease severity. The timing of the development of polyuria was clustered around the diagnosis of vasospasm and patients with polyuria developed vasospasm faster than those without polyuria.

Conclusions

Polyuria is common after aSAH and is significantly associated with cerebral vasospasm. The development of polyuria may be temporally related to the development of vasospasm. An increase in urine volume may be a useful clinical predictor of patients at risk for vasospasm.

Sex differences and the role of IL-10 in ischemic stroke recovery

Females experience poorer recovery after ischemic stroke compared to males, even after controlling for age and stroke severity. IL-10 is an anti-inflammatory cytokine produced by T regulatory cells and Th2 CD4⁺ helper T cells. In ischemic stroke, an excessive IL-10 response contributes to post-stroke immunosuppression, which worsens outcomes. However, it is unknown if sex differences exist in IL-10 levels after ischemic stroke. In this study, we found that higher levels of IL-10 were associated with poor acute and long-term outcomes after ischemic stroke in female patients but not in males. After controlling for confounders, IL-10 was not an independent predictor of functional outcomes. This suggests that higher serum IL-10 levels may reflect factors that interact with sex such as age and stroke severity.

Thyroid hormones and functional outcomes after ischemic stroke

Background

Stroke is the fifth leading cause of death and the primary cause of long-term adult disability in the United States. Increasing evidence suggests that low T3 levels immediately following acute ischemic stroke are associated with greater stroke severity, higher mortality rates, and poorer functional outcomes. Prognosis is also poor in critically ill hospitalized patients who have non-thyroidal illness syndrome (NTIS), where T3 levels are low, but TSH is normal. However, data regarding the association between TSH levels and functional outcomes are contradictory. Thus, this study investigated the role of TSH on stroke outcomes, concomitantly with T3 and T4.

Findings

In this work, blood was collected from patients with radiologically confirmed acute ischemic stroke at 24±6 hours post-symptom onset and serum levels of TSH, free T3, and free T4 were measured. Stroke outcomes were measured at discharge, 3 and 12 months using the modified Rankin scale and modified Barthel Index as markers of disability. Though we found that lower levels of free T3 were associated with worse prognosis at hospital discharge, and at 3 and 12 months post-stroke, none of these outcomes held after multivariate analysis. Thus, it is likely that thyroid hormones are associated with other factors that impact stroke outcomes, such as sex, age and stroke etiology.

Conclusions

This study found that lower levels of free T3 were associated with poorer outcomes at hospital discharge, and at 3 and 12 months post stroke, however, these associations diminished after correction for other known predictors of stroke outcome. Thyroid hormones have a complex relationship with ischemic stroke and stroke recovery, which merits further larger investigations.

General theory of frictional heating with application to rubber friction

The energy dissipation in the contact regions between solids in sliding contact can result in high local temperatures which may strongly effect friction and wear. This is the case for rubber sliding on road surfaces at speeds above 1 mm s(-1). We derive equations which describe the frictional heating for solids with arbitrary thermal properties. The theory is applied to rubber friction on road surfaces and we take into account that the frictional energy is partly produced inside the rubber due to the internal friction of rubber and in a thin (nanometer) interfacial layer at the rubber-road contact region. The heat transfer between the rubber and the road surface is described by a heat transfer coefficient which depends on the sliding speed. Numerical results are presented and compared to experimental data. We find that frictional heating results in a kinetic friction force which depends on the orientation of the sliding block, thus violating one of the two basic Leonardo da Vinci 'laws' of friction.

Prestroke living situation and depression contribute to initial stroke severity and stroke recovery

Substantial evidence from both experimental and clinical studies has demonstrated that social isolation can increase stroke incidence and impair recovery. Social isolation leads to higher rates of recurrent stroke but is often not reported as a risk factor. We examined prospectively collected stroke center database variables, which included prestroke living situation, to determine if social isolation could be determined from existing data using living arrangement as a proxy. Patients were categorized into 4 groups hypothesized to represent increasing levels of social isolation: living with spouse, living with family, living alone with visiting services, and living alone. Initial stroke severity and recovery were measured using the National Institutes of Health Stroke Scale and Barthel Index, respectively. A multivariate model was used to determine the relationship among prestroke living situation, stroke severity, and functional outcome. Patients living alone had less severe strokes on admission and better recovery at 3 months compared with the other cohorts. Patients living alone or those who lived with a spouse had less severe strokes on presentation and better recovery at both 3 and 12 months after stroke compared with the other cohorts. However, on detailed examination, it was found that these patients also had significantly higher prestroke function. Pre-existing depression was significantly higher in women, and depressed patients had poorer outcomes 3 months after stroke. Information regarding isolation is notably absent from most large stroke databases. A more comprehensive evaluation of social interaction should be obtained to more accurately measure social isolation.

Lower NIH stroke scale scores are required to accurately predict a good prognosis in posterior circulation stroke

BACKGROUND

The NIH stroke scale (NIHSS) is an indispensable tool that aids in the determination of acute stroke prognosis and decision making. Patients with posterior circulation (PC) strokes often present with lower NIHSS scores, which may result in the withholding of thrombolytic treatment from these patients. However, whether these lower initial NIHSS scores predict better long-term prognoses is uncertain. We aimed to assess the utility of the NIHSS at presentation for predicting the functional outcome at 3 months in anterior circulation (AC) versus PC strokes.

METHODS

This was a retrospective analysis of a large prospectively collected database of adults with acute ischemic stroke. Univariate and multivariate analyses were conducted to identify factors associated with outcome. Additional analyses were performed to determine the receiver operating characteristic (ROC) curves for NIHSS scores and outcomes in AC and PC infarctions. Both the optimal cutoffs for maximal diagnostic accuracy and the cutoffs to obtain >80% sensitivity for poor outcomes were determined in AC and PC strokes.

RESULTS

The analysis included 1,197 patients with AC stroke and 372 with PC stroke. The median initial NIHSS score for patients with AC strokes was 7 and for PC strokes it was 2. The majority (71%) of PC stroke patients had baseline NIHSS scores ≤4, and 15% of these 'minor' stroke patients had a poor outcome at 3 months. ROC analysis identified that the optimal NIHSS cutoff for outcome prediction after infarction in the AC was 8 and for infarction in the PC it was 4. To achieve >80% sensitivity for detecting patients with a subsequent poor outcome, the NIHSS cutoff for infarctions in the AC was 4 and for infarctions in the PC it was 2.

CONCLUSION

The NIHSS cutoff that most accurately predicts outcomes is 4 points higher in AC compared to PC infarctions. There is potential for poor outcomes in patients with PC strokes and low NIHSS scores, suggesting that thrombolytic treatment should not be withheld from these patients based solely on the NIHSS. © 2014 S. Karger AG, Basel.

β-Blockers associated with no class-specific survival benefit in acute intracerebral hemorrhage

OBJECTIVES

Despite the high mortality, there is currently no specific treatment for intracerebral hemorrhage (ICH). Research investigating optimum degree of blood pressure control in patients presenting with ICH and hypertension is ongoing. However, there is limited understanding of the potential benefits of specific classes of antihypertensive therapy. β-Adrenergic antagonists may provide neuroprotection from inflammation-induced injury by inhibiting sympathetic nervous system mediated immune activation. We examined mortality in ICH patients receiving β-adrenergic antagonists to determine whether this class of antihypertensive therapy was associated with improved survival.

METHODS

A retrospective analysis of a large, prospectively collected database of patients presenting with acute ICH was performed. Patients were grouped by inpatient β-blocker treatment to determine an effect on mortality during the inpatient stay and at 3 months of follow-up. Additional analysis was conducted comparing β-blocker therapy to any other antihypertensive treatment to determine a class-specific association of β-blocker treatment with mortality.

RESULTS

The study population included 426 patients with acute, spontaneous ICH. Inpatient β-blocker use was independently associated with decreased rates of inpatient death and mortality at 3 months of follow-up. However, univariate and multivariable analyses comparing β-blocker use to other antihypertensives failed to show any class-specific reduction in mortality at either time point.

DISCUSSION

Our study demonstrates that the improvement seen in patients treated with β-adrenergic antagonists is not an effect unique to this class. This supports ongoing trials to determine optimum levels of blood pressure control using multiple classes of antihypertensives.

Rubber friction for tire tread compound on road surfaces

We have measured the surface topography and calculated the surface roughness power spectrum for an asphalt road surface. For the same surface we have measured the friction for a tire tread compound for velocities 10(-6) m s(-1) < v < 10(-3) m s(-1) at three different temperatures (at -8 °C, 20 °C and 48 °C). The friction data was shifted using the bulk viscoelasticity shift factor a(T) to form a master curve. We have measured the effective rubber viscoelastic modulus at large strain and calculated the rubber friction coefficient (and contact area) during stationary sliding and compared it to the measured friction coefficient. We find that for the low velocities and for the relatively smooth road surface we consider, the contribution to friction from the area of real contact is very important, and we interpret this contribution as being due to shearing of a very thin confined rubber smear film.

Abstract TP58: NIH Stroke Scale as Predictor of Prognosis in Posterior Circulation Stroke

BACKGROUND: The NIHSS is an indispensable tool that aids in the decision-making of acute stroke management. Posterior circulation strokes often have lower NIHSS scores. This may result in withholding treatment with IV tPA and poor outcome in this population. We aimed to assess the predictive value of the NIHSS on poor functional outcome in anterior circulation (AC) versus posterior circulation (PC) strokes.

METHODS: This was a retrospective analysis of a prospectively collected database from a single center. Adult patients admitted to the stroke service with acute ischemic stroke from January 2000 through December 2011 were included. Data collected included demographics, initial NIHSS, vascular distribution of infarct, complications, and outcome at 3 months. Since this study focused on minor strokes, death or disability was defined as death or a score of < 18 on the modified Barthel Index (BI) scale.

RESULTS: The analysis included 1,197 patients with AC stroke and 372 with PC stroke. Table 1 lists the characteristics of the two groups. The NIHSS score on admission was lower in PC stroke and the majority (63%) of PC stroke patients had baseline NIHSS scores < 4. AC stroke patients were more likely to be treated with IV tPA or endovascular treatment. Surprisingly, 15% of patients with posterior circulation strokes and admission NIHSS score < 4 had death or disability at 3 months. On multivariable analyses, higher NIHSS score was an independent predictor of death or disability at 3 months in both AC (OR 1.20, 95% CI 1.17-1.23, p <0.001) and PC (1.15, 1.08-1.21, p <0.001) stroke. In PC stroke, treatment with IV tPA was a strong predictor of excellent outcome at 3 months (OR 5.62, 95% CI 1.06-29.9, p < 0.05).

CONCLUSION: There is a potential risk for death or disability in patients with PC stroke even with low NIHSS scores. These data suggest that treatment with IV tPA should not be withheld from patients with PC stroke syndromes based on the NIHSS score.

Fine-tuning of substrate architecture and surface chemistry promotes muscle tissue development

Tissue engineering has been increasingly brought to the scientific spotlight in response to the tremendous demand for regeneration, restoration or substitution of skeletal or cardiac muscle after traumatic injury, tumour ablation or myocardial infarction. In vitro generation of a highly organized and contractile muscle tissue, however, crucially depends on an appropriate design of the cell culture substrate. The present work evaluated the impact of substrate properties, in particular morphology, chemical surface composition and mechanical properties, on muscle cell fate. To this end, aligned and randomly oriented micron (3.3±0.8 μm) or nano (237±98 nm) scaled fibrous poly(ε-caprolactone) non-wovens were processed by electrospinning. A nanometer-thick oxygen functional hydrocarbon coating was deposited by a radio frequency plasma process. C2C12 muscle cells were grown on pure and as-functionalized substrates and analysed for viability, proliferation, spatial orientation, differentiation and contractility. Cell orientation has been shown to depend strongly on substrate architecture, being most pronounced on micron-scaled parallel-oriented fibres. Oxygen functional hydrocarbons, representing stable, non-immunogenic surface groups, were identified as strong triggers for myotube differentiation. Accordingly, the highest myotube density (28±15% of total substrate area), sarcomeric striation and contractility were found on plasma-coated substrates. The current study highlights the manifold material characteristics to be addressed during the substrate design process and provides insight into processes to improve bio-interfaces.

Photovoltaic response of carbon nanotube-silicon heterojunctions: effect of nanotube film thickness and number of walls

We report on the multiwall carbon nanotube application as energy conversion material to fabricate thin film solar cells, with nanotubes acting as photogeneration sites as well as charge separators, collectors and carrier transporters. The device consists of a semitransparent thin film of nanotubes coating a n-type crystalline silicon substrate. Under illumination electron-hole (e-h) pairs, generated in the nanotubes and in the silicon substrate underneath, are split and charges are transported through the nanotubes (electrons) and the n-Si (holes). We found that a suitable thickness of the nanotube thin film, high density of Schottky junctions between nanotubes and n-Si and lowest number of nanotube walls are all fundamental parameters to improve the device incident photon to electron conversion efficiency. Multiwall carbon nanotubes have been synthesized by chemical vapour deposition in an ultra high vacuum chamber by evaporating a given amount of iron at room temperature and then exposing the substrate kept at 800 degrees C at acetylene gas. The amount of deposited iron is found to directly affect the nanotube size distribution (inner and outer diameter) and therefore the number of walls of the nanotubes.