Strokes Averted by Intravenous Thrombolysis: A Secondary Analysis of a Prospective, Multicenter, Controlled Trial of Mobile Stroke Units.

OBJECTIVE: This study was undertaken to examine averted stroke in optimized stroke systems. METHODS: This secondary analysis of a multicenter trial from 2014 to 2020 compared patients treated by mobile stroke unit (MSU) versus standard management. The analytical cohort consisted of participants with suspected stroke treated with intravenous thrombolysis. The main outcome was a tissue-defined averted stroke, defined as a final diagnosis of stroke with resolution of presenting symptoms/signs by 24 hours attributed to thrombolysis and no acute infarction/hemorrhage on imaging. An additional outcome was stroke with early symptom resolution, defined as a final diagnosis of stroke with resolution of presenting symptoms/signs by 24 hours attributed to thrombolysis. RESULTS: Among 1,009 patients with a median last known well to thrombolysis time of 87 minutes, 159 (16%) had tissue-defined averted stroke and 276 (27%) had stroke with early symptom resolution. Compared with standard management, MSU care was associated with more tissue-defined averted stroke (18% vs 11%, adjusted odds ratio [aOR] = 1.82, 95% confidence interval [CI] = 1.13-2.98) and stroke with early symptom resolution (31% vs 21%, aOR = 1.74, 95% CI = 1.12-2.61). The relationships between thrombolysis treatment time and averted/early recovered stroke appeared nonlinear. Most models indicated increased odds for stroke with early symptom resolution but not tissue-defined averted stroke with earlier treatment. Additionally, younger age, female gender, hyperlipidemia, lower National Institutes of Health Stroke Scale, lower blood pressure, and no large vessel occlusion were associated with both tissue-defined averted stroke and stroke with early symptom resolution. INTERPRETATION: In optimized stroke systems, 1 in 4 patients treated with thrombolysis recovered within 24 hours and 1 in 6 had no demonstrable brain injury on imaging. ANN NEUROL 2024;95:347-361.

Prospective, Multicenter, Controlled Trial of Mobile Stroke Units.

BACKGROUND: Mobile stroke units (MSUs) are ambulances with staff and a computed tomographic scanner that may enable faster treatment with tissue plasminogen activator (t-PA) than standard management by emergency medical services (EMS). Whether and how much MSUs alter outcomes has not been extensively studied. METHODS: In an observational, prospective, multicenter, alternating-week trial, we assessed outcomes from MSU or EMS management within 4.5 hours after onset of acute stroke symptoms. The primary outcome was the score on the utility-weighted modified Rankin scale (range, 0 to 1, with higher scores indicating better outcomes according to a patient value system, derived from scores on the modified Rankin scale of 0 to 6, with higher scores indicating more disability). The main analysis involved dichotomized scores on the utility-weighted modified Rankin scale (≥0.91 or <0.91, approximating scores on the modified Rankin scale of ≤1 or >1) at 90 days in patients eligible for t-PA. Analyses were also performed in all enrolled patients. RESULTS: We enrolled 1515 patients, of whom 1047 were eligible to receive t-PA; 617 received care by MSU and 430 by EMS. The median time from onset of stroke to administration of t-PA was 72 minutes in the MSU group and 108 minutes in the EMS group. Of patients eligible for t-PA, 97.1% in the MSU group received t-PA, as compared with 79.5% in the EMS group. The mean score on the utility-weighted modified Rankin scale at 90 days in patients eligible for t-PA was 0.72 in the MSU group and 0.66 in the EMS group (adjusted odds ratio for a score of ≥0.91, 2.43; 95% confidence interval [CI], 1.75 to 3.36; P<0.001). Among the patients eligible for t-PA, 55.0% in the MSU group and 44.4% in the EMS group had a score of 0 or 1 on the modified Rankin scale at 90 days. Among all enrolled patients, the mean score on the utility-weighted modified Rankin scale at discharge was 0.57 in the MSU group and 0.51 in the EMS group (adjusted odds ratio for a score of ≥0.91, 1.82; 95% CI, 1.39 to 2.37; P<0.001). Secondary clinical outcomes generally favored MSUs. Mortality at 90 days was 8.9% in the MSU group and 11.9% in the EMS group. CONCLUSIONS: In patients with acute stroke who were eligible for t-PA, utility-weighted disability outcomes at 90 days were better with MSUs than with EMS. (Funded by the Patient-Centered Outcomes Research Institute; BEST-MSU ClinicalTrials.gov number, NCT02190500.).

Golden Hour Treatment With tPA (Tissue-Type Plasminogen Activator) in the BEST-MSU Study.

BACKGROUND: Treatment of patients with acute ischemic stroke on mobile stroke units (MSUs) improves outcomes compared with management by standard emergency medical services ambulances and is associated with more patients treated with intravenous tPA (tissue-type plasminogen activator) in the first golden hour after last known normal. We explored the predictors and outcomes of first-hour treatment (FHT) compared with later treatment in an alternating-week cluster-controlled trial of MSUs. METHODS: We analyzed all patients treated with intravenous tPA in the BEST-MSU Study (Benefits of Stroke Treatment Delivered by a Mobile Stroke Unit Compared to Standard Management by Emergency Medical Services). After stratifying by treatment timeframe, we identified factors associated with FHT. We performed adjusted analyses of the association between FHT and clinical outcome and modeled the shape of the relationship between last known normal-to-treatment time and excellent outcome. RESULTS: Among 941 tPA-treated patients, 206 (21.8%) had lytic started within 60 minutes. Treatment on the MSU, older age, male sex, alert by 911, faster arrival on-scene and imaging, more severe stroke, atrial fibrillation, and absence of heart failure and pretreatment antihypertensive treatment were associated with FHT. Compared with later treatment, FHT was associated with higher adjusted odds ratio for 90-day modified Rankin Scale score of 0 to 1 (odds ratio, 1.87 [95% CI, 1.25-2.84]; P=0.003). Among FHT patients, 68% achieved a 90-day modified Rankin Scale of 0 or 1 or returned to their baseline status. FHT was not associated with higher risk of hemorrhage and was associated with reduced risk of treating neurovascular mimics. CONCLUSIONS: FHT almost doubles the odds of excellent clinical outcome without increased risk compared with later treatment, which supports the use of MSUs.

Hemorrhage Enlargement Is More Frequent in the First 2 Hours: A Prehospital Mobile Stroke Unit Study.

BACKGROUND: Hematoma enlargement (HE) after intracerebral hemorrhage (ICH) is a therapeutic target for improving outcomes. Hemostatic therapies to prevent HE may be more effective the earlier they are attempted. An understanding of HE in first 1 to 2 hours specifically in the prehospital setting would help guide future treatment interventions in this time frame and setting. METHODS: Patients with spontaneous ICH within 4 hours of symptom onset were prospectively evaluated between May 2014 and April 2020 as a prespecified substudy within a multicenter trial of prehospital mobile stroke unit versus standard management. Baseline computed tomography scans obtained <1, 1 to 2, and 2 to 4 hours postsymptom onset on the mobile stroke unit in the prehospital setting were compared with computed tomography scans repeated 1 hour later and at 24 hours in the hospital. HE was defined as >6 mL if baseline ICH volume was <20 mL and 33% increase if baseline volume >20 mL. The association between time from symptom onset to baseline computed tomography (hours) and HE was investigated using Wilcoxon rank-sum test when time was treated as a continuous variable and using Fisher exact test when time was categorized. Kruskal-Wallis and Wilcoxon rank-sum tests evaluated differences in baseline volumes and HE. Univariable and multivariable logistic regression analyses were conducted to identify factors associated with HE and variable selection was performed using cross-validated L1-regularized (Lasso regression). This study adhered to STROBE guidelines (Strengthening the Reporting of Observational Studies in Epidemiology) for cohort studies. RESULTS: One hundred thirty-nine patients were included. There was no difference between baseline ICH volumes obtained <1 hour (n=43) versus 1 to 2 hour (n=51) versus >2 hours (n=45) from symptom onset (median [interquartile range], 13 mL [6-24] versus 14 mL [6-30] versus 12 mL [4-19]; P=0.65). However, within the same 3 time epochs, initial hematoma growth (volume/time from onset) was greater with earlier baseline scanning (median [interquartile range], 17 mL/hour [9-35] versus 9 mL/hour [5-23]) versus 4 mL/hour [2-7]; P<0.001). Forty-nine patients had repeat scans 1 hour after baseline imaging (median, 2.3 hours [interquartile range. 1.9-3.1] after symptom onset). Eight patients (16%) had HE during that 1-hour interval; all of these occurred in patients with baseline imaging within 2 hours of onset (5/18=28% with baseline imaging within 1 hour, 3/18=17% within 1-2 hour, 0/13=0% >2 hours; P=0.02). HE did not occur between the scans repeated at 1 hour and 24 hours. No association between baseline variables and HE was detected in multivariable analyses. CONCLUSIONS: HE in the next hour occurs in 28% of ICH patients with baseline imaging within the first hour after symptom onset, and in 17% of those with baseline imaging between 1 and 2 hours. These patients would be a target for ultraearly hemostatic intervention.

How Frequent is the One-Hour tPA Infusion Interrupted or Delayed?

BACKGROUND AND PURPOSE: Tissue plasminogen activator (tPA) requires a one-hour infusion after the bolus. The frequency of delay or interruption of the tPA infusion may be useful in weighing the advantages of Tenecteplase (TNKase, TNK) which does not require an infusion. METHODS: Utilizing the Benefits of Stroke Treatment Delivered Using a Mobile Stroke Unit Compared to Standard Management by Emergency Medical Services study database, we calculated the frequency and magnitude of tPA infusion delay or interruption. RESULTS: Of 497 patients treated with tPA on the Houston Mobile Stroke Unit (MSU), 41 (8.3%) had delay or interruption of the infusion for reasons that did not reflect a side effect of, or contraindication to, tPA. Nine received less than 90% of their calculated dose (median 62%, range 28-88%), and eleven had more than a 10% prolongation of their infusion (median 19 min, range 7-210 min). Six patients (1.2%) had infusion stopped for a valid concern for tPA side effect or contraindication. CONCLUSIONS: Interruption or discontinuation of the tPA infusion occurs in 8% of patients treated on a MSU providing an opportunity for more complete and faster treatment with TNK.

Retrospectively Collected EQ-5D-5L Data as Valid Proxies for Imputing Missing Information in Longitudinal Studies.

OBJECTIVES: Studies face challenges with missing 5-level EQ-5D (EQ-5D-5L) data, often because of the need for longitudinal EQ-5D-5L data collection. There is a dearth of validated methodologies for dealing with missing EQ-5D-5L data in the literature. This study, for the first time, examined the possibility of using retrospectively collected EQ-5D-5L data as proxies for the missing data. METHODS: Participants who had prospectively completed a 3rd month postdischarge EQ-5D-5L instrument (in-the-moment collection) were randomly interviewed to respond to a 2nd "retrospective collection" of their 3rd month EQ-5D-5L at 6th, 9th, or 12th month after hospital discharge. A longitudinal single imputation was also used to assess the relative performance of retrospective collection compared with the longitudinal single imputation. Concordances between the in-the-moment, retrospective, and imputed measures were assessed using intraclass correlation coefficients and weighted kappa statistics. RESULTS: Considerable agreement was observed on the basis of weighted kappa (range 0.72-0.95) between the mobility, self-care, and usual activities dimensions of EQ-5D-5L collected in-the-moment and retrospectively. Concordance based on intraclass correlation coefficients was good to excellent (range 0.79-0.81) for utility indices computed, and excellent (range 0.93-0.96) for quality-adjusted life-years computed using in-the-moment compared with retrospective EQ-5D-5L. The longitudinal single imputation did not perform as well as the retrospective collection method. CONCLUSIONS: This study demonstrates that retrospective collection of EQ-5D-5L has high concordance with "in-the-moment" EQ-5D-5L and could be a valid and attractive alternative for data imputation when longitudinally collected EQ-5D-5L data are missing. Future studies examining this method for other disease areas and populations are required to provide more generalizable evidence.

Mobile Stroke Unit Computed Tomography Angiography Substantially Shortens Door-to-Puncture Time.

Background and Purpose- Endovascular thrombectomy (ET) door-to-puncture time (DTPT) is a modifiable metric. One of the most important, yet time-consuming steps, is documentation of large vessel occlusion by computed tomography angiography (CTA). We hypothesized that obtaining CTA on board a Mobile Stroke Unit and direct alert of the ET team shortens DTPT by over 30 minutes. Methods- We compared DTPT between patients having CTA onboard the Mobile Stroke Unit then subsequent ET from September 2018 to November 2019 and patients in Mobile Stroke Unit from August 2014 to August 2018, when onboard CTA was not yet being used. We also correlated DTPT with change in National Institutes of Health Stroke Scale between baseline and 24 hours. Results- Median DTPT was 53.5 (95% CI, 35-67) minutes shorter with onboard CTA and direct ET team notification: 41 minutes (interquartile range, 30.0-63.5) versus 94.5 minutes (interquartile range, 69.8-117.3; P<0.001). Median on-scene time was 31.5 minutes (interquartile range, 28.8-35.5) versus 27.0 minutes (interquartile range, 23.0-31.0) (P<0.001). Shorter DTPT correlated with greater improvement of National Institutes of Health Stroke Scale (correlation=-0.2, P=0.07). Conclusions- Prehospital Mobile Stroke Unit management including on-board CTA and ET team alert substantially shortens DTPT. Registration- URL: https://clinicaltrials.gov; Unique identifier: NCT02190500.

Retrospective collection of 90-day modified Rankin Scale is accurate.

BACKGROUND: The 90-day modified Rankin Scale is a widely used outcome after stroke but is sometimes hard to ascertain due to loss to follow-up. Missing outcomes can result in biased and/or inefficient estimates in clinical trials. The aim of this study is to assess the validity of acquiring the 90-day modified Rankin Scale at a later point of time when the patient has been lost at 90 days to impute the missing value. METHODS: Participants who had prospectively completed a 90-day modified Rankin Scale questionnaire on their own in the Benefits of Stroke Treatment Using a Mobile Stroke Unit study were randomly interviewed to recall the 90-day modified Rankin Scale at 6, 9, or 12 months after hospital discharge over the phone. Concordance between the two scores was assessed using kappa and weighted kappa statistics. Logistic regression was used to identify factors associated with inconsistent reporting of the 90-day modified Rankin Scale. RESULTS: Substantial agreement was observed between in-the-moment and retrospective 90-day modified Rankin Scale recalled at 6, 9, or 12 months (weighted kappa = 0.93, 95% confidence interval: 0.89-0.98; weighted kappa = 0.93, 95% confidence interval: 0.85-1.00 and weighted kappa = 0.89, 95% confidence interval: 0.82-0.95, respectively). CONCLUSION: Retrospective recall of 90-day modified Rankin Scale at a later time point is a valid means to impute missing data in stroke clinical trials.

Enhanced dispatch and rendezvous doubles the catchment area and number of patients treated on a mobile stroke unit.

INTRODUCTION: Mobile Stroke Units (MSUs) deliver acute stroke treatment on-scene in coordination with Emergency Medical Services (EMS). One criticism of the MSU approach is the limited range of a single MSU. The Houston MSU is evaluating MSU implementation, and we developed a rendezvous approach as an innovative solution to expand the range and number of patients treated. METHODS: In addition to direct 911 dispatch of our MSU to the scene within our 7-mile catchment area, we empowered more distant EMS units to activate the MSU. We also monitored EMS radio communications to identify possible patients. For these distant patients, the MSU met the EMS unit en route to the stroke center and treated the patient at that intermediate location. The distribution of the distance from MSU base station to site of stroke and time from 911 alert to tissue plasminogen activator (tPA) bolus were compared between patients treated on-scene and by rendezvous using Wilcoxon rank sum test. RESULTS: Over 4 years, 338 acute ischemic stroke patients were treated with tPA on our MSU. Of these, 169 (50%) were treated on-scene after MSU dispatch at a median of 6.4 miles (IQR 6.4 miles) from MSU base station. 169 (50%) were treated by 'rendezvous' pathway with assessment and treatment of stroke a median of 12.4 miles from base (IQR 5.5 miles) (p< 0.0001). Time (min) from MSU alert to tPA bolus did not differ: 36.0 ± 10.0 for on-scene vs 37.0 ± 10.0 with rendezvous (p=0.65). 13% of patients alerted via direct 911 dispatch were treated vs 44% of rendezvous patients. CONCLUSION: Adding a rendezvous approach to an MSU dispatch pathway doubles the range of operations and the number of patients treated by an MSU in an urban area, without incurring delay.

Emergency Department Door-to-Puncture Time Since 2014.

Background and Purpose- The impact of a mobile stroke unit (MSU) on access to intraarterial thrombectomy (IAT) is a prespecified BEST-MSU substudy (Benefits of Stroke Treatment Delivered Using a Mobile Stroke Unit Compared to Standard Management by Emergency Medical Services). On the MSU, IAT decision-making steps, such as computed tomography, neurological exam, and tPA (tissue-type plasminogen activator) treatment are completed before emergency department arrival. We hypothesized that such pre-ED assessment of potential IAT patients on an MSU improves the time from ED arrival to skin puncture time (door-to-puncture-time, DTPT). Methods- BEST-MSU is a prospective comparative effectiveness study of MSU versus standard management by emergency medical services (EMS). We compared ED DTPT among the following groups of MSU and EMS patients: all IAT patients, IAT patients post-tPA, and IAT patients post-tPA meeting thrombolytic adjudication criteria over the first 4 years of the study. Results- From August 2014 to July 2018, a total of 161 patients underwent IAT. Ninety-four patients presented to the ED via the MSU and 67 by EMS. One hundred forty patients received tPA before IAT, 85 in the MSU arm, and 55 in the EMS arm. One hundred twenty-six patients received tPA within thrombolytic adjudication criteria: 76 MSU and 50 EMS. DTPT in minutes was shorter for MSU patients (all IAT MSU versus EMS 89 versus 99, P=0.01; IAT post-tPA MSU versus EMS 93 versus 100, P=0.03; and IAT post-tPA within adjudicated criteria MSU versus EMS 93 versus 99.5, P=0.03). From 2014 to 2018, DTPT decreased at a faster rate for EMS compared with MSU-managed patients, improving by about an hour. Conclusions- Pre-ED IAT evaluation on an MSU results in faster DTPT compared with arrival by EMS. Since 2014, dramatic improvement in ED IAT metrics has attenuated this difference. However, DTPT in all groups indicates substantial room for improvement.

Time to Decision and Treatment With tPA (Tissue-Type Plasminogen Activator) Using Telemedicine Versus an Onboard Neurologist on a Mobile Stroke Unit.

BACKGROUND AND PURPOSE: Mobile stroke units (MSUs) can speed treatment with intravenous tPA (tissue-type plasminogen activator). We previously showed substantial agreement between a telemedicine-based vascular neurologist (TM-VN) and an onboard vascular neurologist (OB-VN) for the evaluation of patients with stroke for tPA eligibility on an MSU. However, the time efficiency of the telemedicine-based evaluation remained uncertain. In this study, we examined the speed of decision and treatment from MSU arrival for the TM-VN compared with an OB-VN. METHODS: In 50 consecutive situations, the TM-VN served as the primary decision maker. Times from MSU arrival to tPA decision and tPA bolus were compared with the same metrics for when the OB-VN served as the primary decision maker. RESULTS: Time to tPA decision for the TM-VN was 21 minutes (interquartile range, 16.25-26) versus 18 minutes (interquartile range, 14-22) for the OB-VN (P=0.01). Initiation of tPA bolus was 24 minutes (interquartile range, 19.75-30) for the TM-VN versus 24 minutes (interquartile range, 19-27.75) for the OB-VN (P=0.5). CONCLUSIONS: Assessment by a TM-VN is comparable with an OB-VN in making decisions about tPA administration on an MSU and does not lead to treatment delays. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02190500.

Design of a novel continuous flow reactor for low pH viral inactivation.

Insufficient mixing in laminar flow reactors due to diffusion-dominated flow limits their use in applications where narrow residence time distribution (RTD) is required. The aim of this study was to design and characterize a laminar flow (Re 187.7-375.5) tubular reactor for low pH viral inactivation with enhanced radial mixing via the incorporation of curvature and flow inversions. Toward this aim, the reactor described here, Jig in a Box (JIB), was designed with a flow path consisting of alternating 270° turns. The design was optimized by considering the strength of secondary flows characterized by the Dean No., the corresponding secondary flow development length, and the reactor turn lengths. Comprehensive CFD analysis of the reactor centerline velocity profile, cross-sectional velocity, and secondary flow streamlines confirmed enhanced radial mixing due to secondary flows and changes in flow direction. For initial CFD and experimental studies the reactor was limited to a 16.43 m length. Pulse tracer studies for the reactor were computationally simulated and experimentally generated to determine the RTD, RTD variance, and minimum residence time for the tracer fluid elements leaving the reactor, as well as to validate the computational model. The reactor was scaled length wise to increase incubation time and it was observed that as the reactor length increases the RTD variance increases linearly and the dimensionless RTD profile becomes more symmetrical and tighter about the mean residence time.

Telemedicine Can Replace the Neurologist on a Mobile Stroke Unit.

BACKGROUND AND PURPOSE: The BEST-MSU study (Benefits of Stroke Treatment Delivered Using a Mobile Stroke Unit) is a comparative effectiveness trial in patients randomized to mobile stroke unit or standard management. A substudy tested interrater agreement for tissue-type plasminogen activator eligibility between a telemedicine vascular neurologist and onboard vascular neurologist. METHODS: On scene, both the telemedicine vascular neurologist and onboard vascular neurologist independently evaluated the patient, documenting their tissue-type plasminogen activator treatment decision, National Institutes of Health Stroke Scale score, and computed tomographic interpretation. Agreement was determined using Cohen κ statistic. Telemedicine-related technical failures that impeded remote assessment were recorded. RESULTS: Simultaneous and independent telemedicine vascular neurologist and onboard vascular neurologist assessment was attempted in 174 patients. In 4 patients (2%), the telemedicine vascular neurologist could not make a decision because of technical problems. The telemedicine vascular neurologist agreed with the onboard vascular neurologist on 88% of evaluations (κ=0.73). CONCLUSIONS: Remote telemedicine vascular neurologist assessment is reliable and accurate, supporting either telemedicine vascular neurologist or onboard vascular neurologist assessment on our mobile stroke unit. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02190500.

Thrombelastography does not predict clinical response to rtPA for acute ischemic stroke.

Thrombelastography (TEG) measures coagulation in venous blood. We hypothesized that TEG, by reflecting clot subtype and ex vivo fibrinolysis, might predict fibrinolytic response to tPA as reflected by rapid clinical improvement or hemorrhagic transformation of the infarct. 171 acute ischemic stroke patients treated with tPA were prospectively enrolled. Venous blood for TEG was drawn before and 10 min after tPA bolus. We measured rapid clinical improvement (RCI = 8 point improvement on NIHSS or total NIHSS of 0, 1 at 36 h), Hemorrhagic transformation (HT = any blood on imaging within 36 h), and hyperdense middle cerebral artery sign (HDMCA = biomarker for erythrocyte-rich clot). Multivariable regression models compared TEG parameters after adjusting for potential confounders. No differences in pre- or post-tPA TEG were found between patients with or without RCI. Also, there was no correlation between TEG and HDMCA. Clotting was slightly prolonged in patients with HT (p = 0.046). We failed to find a robust association between TEG and clinical response to tPA. It is likely that arterial clot lysis is determined by factors unrelated to coagulation status as measured by TEG in the venous circulation. It is unlikely that TEG will be useful to predict clinical response to tPA, but may help predict bleeding.

Establishing the first mobile stroke unit in the United States.

BACKGROUND AND PURPOSE: Recently, the Mobile Stroke Unit (MSU) concept was introduced in Germany demonstrating prehospital treatment of more patients within the first hour of symptom onset. However, the details and complexities of establishing such a program in the United States are unknown. We describe the steps involved in setting up the first MSU in the United States. METHODS: Implementation included establishing leadership, fund-raising, purchase and build-out, knitting a collaborative consortium of community stakeholders, writing protocols to ensure accountability, radiation safety, purchasing supplies, licensing, insurance, establishing a base station, developing a communication plan with city Emergency Medical Services, Emergency Medical Service training, staffing, and designing a research protocol. RESULTS: The MSU was introduced after ≈1 year of preparation. Major obstacles to establishing the MSU were primarily obtaining funding, licensure, documenting radiation safety protocols, and establishing a smooth communication system with Emergency Medical Services. During an 8 week run-in phase, ≈2 patients were treated with recombinant tissue-type plasminogen activator per week, one-third within 60 minutes of symptom onset, with no complications. A randomized study to determine clinical outcomes, telemedicine reliability and accuracy, and cost effectiveness was formulated and has begun. CONCLUSION: The first MSU in the United States has been introduced in Houston, TX. The steps needed to accomplish this are described.

Thrombelastography detects the anticoagulant effect of rivaroxaban in patients with stroke.

BACKGROUND AND PURPOSE: Factor Xa inhibitors are prescribed for stroke prevention in atrial fibrillation. Managing such patients is challenging especially if they are eligible for thrombolysis because there is no rapidly available test to detect the effect of such medications. Thrombelastography analyzes the dynamics of coagulation and can be rapidly performed. We sought to determine whether thrombelastography can detect the anticoagulation effect of factor Xa inhibitors in patients with stroke. METHODS: Blood from 10 patients with stroke was analyzed by thrombelastography at baseline and 2 to 18 hours after rivaroxaban administration. RESULTS: Increased R, K, and δ were seen at 2, 4, and 6 hours, while G, maximum amplitude, α-angle, and LY30 were decreased. Baseline R was 5.8±0.5 when compared with 11.4±1.0 at 2 hours. R remained prolonged at 18 hours. Other thrombelastography parameters were normal by 18 hours. CONCLUSIONS: Thrombelastography can detect the anticoagulant effect of factor Xa inhibitors in patients with stroke and might be useful in the emergency management of those eligible for thrombolysis.

Thrombelastography detects possible coagulation disturbance in patients with intracerebral hemorrhage with hematoma enlargement.

BACKGROUND AND PURPOSE: Intracerebral hemorrhage (ICH) has high morbidity, and hematoma enlargement (HE) causes worse outcome. Thrombelastography (TEG) measures the dynamics of clot formation and dissolution, and might be useful for assessing bleeding risk. We used TEG to detect changes in clotting in patients with and without HE after ICH. METHODS: This prospective study included 64 patients with spontaneous ICH admitted from 2009 to 2013. TEG was performed within 6 hours of symptom onset and after 36 hours. Brain imaging was obtained at baseline and at 36±12 hours, and HE was defined as total volume increase>6 cc or >33%. TEG was also obtained from 57 controls. RESULTS: Compared with controls, patients with ICH demonstrated faster and stronger clot formation; shorter R and delta (P<0.0001) at baseline; and higher MA and G (P<0.0001) at 36 hours; 11 patients had HE. After controlling for potential confounders, baseline K and delta were longer in HE+ compared with HE- patients, indicating that HE+ patients had slower clot formation (P<0.05). TEG was not different between HE+ and HE- patients at 36 hours. CONCLUSIONS: TEG may detect important coagulation changes in patients with ICH. Clotting may be faster and stronger in immediate response to ICH, and a less robust response may be associated with HE. These findings deserve further investigation.

Iodinated contrast does not alter clotting dynamics in acute ischemic stroke as measured by thromboelastography.

BACKGROUND AND PURPOSE: Iodinated contrast agents used for computed tomography angiography (CTA) may alter fibrin fiber characteristics and decrease fibrinolysis by tissue plasminogen activator (tPA). Thromboelastography (TEG) measures the dynamics of coagulation and correlates with thrombolysis in acute ischemic stroke patients. We hypothesized that receiving CTA before tPA will not impair thrombolysis as measured by TEG. METHODS: Acute ischemic stroke patients receiving 0.9 mg/kg tPA <4.5 hours of symptom onset were prospectively enrolled. For CTA, 350 mg/dL of iohexol or 320 mg/dL of iodixanol at a dose of 2.2 mL/kg was administered. TEG was measured before tPA and 10 minutes after tPA bolus. CTA timing was left to the discretion of the treating physician. RESULTS: Of 136 acute ischemic stroke patients who received tPA, 47 had CTA before tPA bolus, and 42 had either CTA after tPA and post-tPA TEG draw or no CTA (noncontrast group). Median change in clot lysis (LY30) after tPA was 95.3% in the contrast group versus 95.0% in the noncontrast group (P=0.74). Thus, tPA-induced thrombolysis did not differ between contrast and noncontrast groups. Additionally, there was no effect of contrast on any pre-tPA TEG value. CONCLUSIONS: Our data do not support an effect of iodinated contrast agents on clot formation or tPA activity.

Secreted production of assembled Norovirus virus-like particles from Pichia pastoris.

BACKGROUND: Norovirus virus-like particles (NoV VLPs) have recently been explored as potential vaccine platforms due to their ability to produce an effective immune response. Expression of the main structural protein, VP1, leads to formation of self-assembled particles with similar characteristics to the original virus. These NoV VLPs have been expressed in Escherichia coli, yeast and insect cells. Expression in E. coli and insect cells share downstream processing issues due to the presence of inclusion bodies or the need for numerous purification steps. NoV VLPs have also been produced in the yeast P. pastoris; however the protein was only expressed intracellularly. RESULTS: We have successfully expressed and secreted the VP1 protein in the novel P. pastoris strain, Bg11, using the methanol inducible pJ912 expression vector, containing the cDNA of NoV VP1. Expression of the VP1 protein in Bg11 was carried out in a 1.5 L bioreactor resulting in a total yield of NoV VLPs greater than 0.6 g/L. NoV VLPs obtained from the culture supernatant were purified via ion-exchange chromatography, resulting in particles with a purity over 90%. The average size of the particles after purification was 40 nm. Transmission electron microscopy was used to visualize the morphology of the particles and saliva-binding assay confirmed that the NoV VLPs bind to Histo-Blood Group Antigens (HBGA). CONCLUSIONS: In this study we describe the expression and characterization of fully assembled Norovirus virus-like particles obtained from P. pastoris. The particles are similar in size, morphology and binding capacity, as previously described, for the original NoV. Our results detail the successful expression and secretion of VLPs in P. pastoris, improving their candidacy as a vaccine platform.

Design, production, and characterization of a single-chain variable fragment (ScFv) derived from the prostate specific membrane antigen (PSMA) monoclonal antibody J591.

A single chain variable fragment (J591 ScFv) that recognizes the extracellular glyco-protein prostate specific membrane antigen (PSMA) was designed, constructed, and expressed in Pichia pastoris. Construction of the J591 ScFv was based on the reported complementarity-determining region (CDR) of the PSMA specific J591 monoclonal antibody (mAb). The nucleotide sequence encoding the J591-derived ScFv was codon-optimized for expression in P. pastoris and a 6× his-tag was added to facilitate affinity purification. A down-scale 2L methanol-induced P. pastoris fermentation yielded 330mg of total protein following a 96h induction. Following Immobolized Metal Affinity Chromatography, functionality of the J591 ScFv was confirmed via Western blot, immunoblot, binding studies, and flow cytometry analysis. The J591 ScFv showed binding affinity and specificity to cell extracts containing PSMA and PSMA-expressing prostate cancer cells. Our results demonstrate that functional J591 ScFv can be produced in P. pastoris for use in diagnostic and targeted therapeutic applications.