Benjamin Winter

Physical Activity Improves Long-Term Stroke Outcome via Endothelial Nitric Oxide Synthase–Dependent Augmentation of Neovascularization and Cerebral Blood Flow

Physical activity upregulates endothelial nitric oxide synthase (eNOS), improves endothelium function, and protects from vascular disease. Here, we tested whether voluntary running would enhance neovascularization and long-term recovery following mild brain ischemia. Wild-type mice were exposed to 30 minutes of middle-cerebral artery occlusion (MCAo) and reperfusion. Continuous voluntary running on wheels conferred long-term upregulation of eNOS in the vasculature and of endothelial progenitor cells (EPCs) in the spleen and bone marrow (BM). This was associated with higher numbers of circulating EPCs in the blood and enhanced neovascularization. Moreover, engraftment of TIE2/LacZ-positive BM-derived cells was increased in the ischemic brain. Four weeks after the insult, trained animals showed higher numbers of newly generated cells in vascular sites, increased density of perfused microvessels and sustained augmentation of cerebral blood flow within the ischemic striatum. Moreover, running conferred tissue sparing and improved functional outcome at 4 weeks. The protective effects of running on angiogenesis and outcome were completely abolished when animals were treated with a NOS inhibitor or the antiangiogenic compound endostatin after brain ischemia, and in animals lacking eNOS expression. Voluntary physical activity improves long-term stroke outcome by eNOS-dependent mechanisms related to improved angiogenesis and cerebral blood flow.

Prehospital thrombolysis in acute stroke Results of the PHANTOM-S pilot study

Objective: Beneficial effects of IV tissue plasminogen activator (tPA) in acute ischemic stroke are strongly time-dependent. In the Pre-Hospital Acute Neurological Treatment and Optimization of Medical care in Stroke (PHANTOM-S) study, we undertook stroke treatment using a specialized ambulance, the stroke emergency mobile unit (STEMO), to shorten call-to-treatment time. Methods: The ambulance was staffed with a neurologist, paramedic, and radiographer and equipped with a CT scanner, point-of-care laboratory, and a teleradiology system. It was deployed by the dispatch center whenever a specific emergency call algorithm indicated an acute stroke situation. Study-specific procedures were restricted to patients able to give informed consent. We report feasibility, safety, and duration of procedures regarding prehospital tPA administration. Results: From February 8 to April 30, 2011, 152 subjects were treated in STEMO. Informed consent was given by 77 patients. Forty-five (58%) had an acute ischemic stroke and 23 (51%) of these patients received tPA. The mean call-to-needle time was 62 minutes compared with 98 minutes in 50 consecutive patients treated in 2010. Two (9%) of the tPA-treated patients had a symptomatic intracranial hemorrhage and 1 of these patients (4%) died in hospital. Technical failures encountered were 1 CT dysfunction and 2 delayed CT image transmissions. Conclusions: The data suggest that prehospital stroke care in STEMO is feasible. No safety concerns have been raised so far. This new approach using prehospital tPA may be effective in reducing call-to-needle times, but this is currently being scrutinized in a prospective controlled study.

Folate Deficiency Induces Neurodegeneration and Brain Dysfunction in Mice Lacking Uracil DNA Glycosylase

Folate deficiency and resultant increased homocysteine levels have been linked experimentally and epidemiologically with neurodegenerative conditions like stroke and dementia. Moreover, folate deficiency has been implicated in the pathogenesis of psychiatric disorders, most notably depression. We hypothesized that the pathogenic mechanisms include uracil misincorporation and, therefore, analyzed the effects of folate deficiency in mice lacking uracil DNA glycosylase (Ung−/−) versus wild-type controls. Folate depletion increased nuclear mutation rates in Ung−/− embryonic fibroblasts, and conferred death of cultured Ung−/− hippocampal neurons. Feeding animals a folate-deficient diet (FD) for 3 months induced degeneration of CA3 pyramidal neurons in Ung−/− but not Ung+/+ mice along with decreased hippocampal expression of brain-derived neurotrophic factor protein and decreased brain levels of antioxidant glutathione. Furthermore, FD induced cognitive deficits and mood alterations such as anxious and despair-like behaviors that were aggravated in Ung−/− mice. Independent of Ung genotype, FD increased plasma homocysteine levels, altered brain monoamine metabolism, and inhibited adult hippocampal neurogenesis. These results indicate that impaired uracil repair is involved in neurodegeneration and neuropsychiatric dysfunction induced by experimental folate deficiency.

Selective neuronal vulnerability following mild focal brain ischemia in the mouse.

The evolution of cellular damage over time and the selective vulnerability of different neuronal subtypes was characterized in the striatum following 30‐minute middle cerebral artery occlusion and reperfusion in the mouse. Using autoradiography we found an increase in the density of [3H]PK11195 binding sites—likely reflecting microglial activation—in the lesion border at 3 days and in the whole striatum from 10 days to 6 weeks. This was accompanied by a distinct loss of [3H]flumazenil and [3H]CGP39653 binding sites from 10 days up to 6 weeks reflecting neuronal loss. Brain ischemia resulted in a substantial loss of medium spiny projection neurons as seen at three days by Nissl staining, TUNEL and immunocytochemistry using antibodies against microtubule‐associated protein (MAP2), NeuN, (μ‐opioid receptors, substance P, Lenkephalin, neurokinin B, choline acetyltransferase, parvalbumin, calretinin and somatostatin. Both patch and matrix compartments were involved in ischemic damage. In contrast, the numbers of cholinergic, GABAergic, and somatostatin‐containing interneurons in the ischemic striatum were not different from those in the contralateral hemisphere at 3 and 14 days. A low density of glutamate receptors, the ability to sequester calcium by calcium‐binding proteins and other hitherto unidentified factors may explain this relative resistance of interneurons to acute ischemia.

Dysexecutive syndrome after mild cerebral ischemia? Mice learn normally but have deficits in strategy switching

Background and Purpose— We determined long-term functional outcome in a well-characterized mouse model of mild focal cerebral ischemia. Methods— We subjected 129/SV mice to sham operation or 30 minutes of left middle cerebral artery occlusion (MCAo) followed by reperfusion (89% survival rate). Six weeks later, animals were tested for neurological deficits, motor coordination on an accelerating Rota-rod apparatus, and spatial navigation in a water maze task. Brain lesion size was determined on NeuN-immunostained coronal brain sections by computer-assisted volumetry. Results— Mice had mild but distinct neurological deficits and no deficits in Rota-rod coordination or swimming speed 6 weeks after MCAo. Moreover, mice had normal spatial learning abilities in the place task. However, stroke mice had deficits in the probe trial and visible platform task, which correlated with striatal lesion size determined on NeuN-immunostained sections. Conclusions— After mild ischemia, mice recover with mild neurological deficits and normal motor coordination. Stroke mice have no obvious deficits in spatial learning in the Morris water maze but display distinct deficits related to strategy switching and relearning.

Improved Prehospital Triage of Patients With Stroke in a Specialized Stroke Ambulance: Results of the Pre-Hospital Acute Neurological Therapy and Optimization of Medical Care in Stroke Study

Background and Purpose— Specialized management of patients with stroke is not available in all hospitals. We evaluated whether prehospital management in the Stroke Emergency Mobile (STEMO) improves the triage of patients with stroke. Methods— STEMO is an ambulance staffed with a specialized stroke team and equipped with a computed tomographic scanner and point-of-care laboratory. We compared the prehospital triage of patients with suspected stroke at dispatcher level who either received STEMO care or conventional care. We assessed transport destination in patients with different diagnoses. Status at hospital discharge was used as short-term outcome. Results— From May 2011 to January 2013, 1804 of 6182 (29%) patients received STEMO care and 4378 of 6182 (71%) patients conventional care. Two hundred forty-five of 2110 (11.6%) patients with cerebrovascular events were sent to hospitals without Stroke Unit in conventional care when compared with 48 of 866 (5.5%; P<0.01%) patients in STEMO care. In patients with ischemic stroke, STEMO care reduced transport to hospitals without Stroke Unit from 10.1% (151 of 1497) to 3.9% (24 of 610; P<0.01). The delivery rate of patients with intracranial hemorrhage to hospitals without neurosurgery department was 43.0% (65 of 151) in conventional care and 11.3% (7 of 62) in STEMO care (P<0.01). There was a slight trend toward higher rates of patients discharged home in neurological patients when cared by STEMO (63.5% versus 60.8%; P=0.096). Conclusions— The triage of patients with cerebrovascular events to specialized hospitals can be improved by STEMO ambulances. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01382862.

Copeptin Levels in Patients With Acute Ischemic Stroke and Stroke Mimics

Background and Purpose— Copeptin levels are increased in patients diagnosed with stroke and other vascular diseases. Copeptin elevation is associated with adverse outcome, predicts re-events in patients with transient ischemic attack and is used in ruling-out acute myocardial infarction. We evaluated whether copeptin can also be used as a diagnostic marker in the prehospital stroke setting. Methods— We prospectively examined patients with suspected stroke on the Stroke Emergency Mobile—an ambulance that is equipped with computed tomography and point-of-care laboratory. A blood sample was taken from patients immediately after arrival. We analyzed copeptin levels in patients with final hospital-based diagnosis of stroke or stroke mimics as well as in vascular or nonvascular patients. In addition, we examined the associations of symptom onset with copeptin levels and the prognostic value of copeptin in patients with stroke. Results— Blood samples of 561 patients were analyzed. No significant differences were seen neither between cerebrovascular (n=383) and other neurological (stroke mimic; n=90) patients (P=0.15) nor between vascular (n=391) and nonvascular patients (n=170; P=0.57). We could not detect a relationship between copeptin levels and time from onset to blood draw. Three-month survival status was available in 159 patients with ischemic stroke. Copeptin levels in nonsurviving patients (n=8: median [interquartile range], 27.4 [20.2–54.7] pmol/L) were significantly higher than in surviving patients (n=151: median [interquartile range], 11.7 [5.2–30.9] pmol/L; P=0.024). Conclusions— In the prehospital setting, copeptin is neither appropriate to discriminate between stroke and stroke mimic patients nor between vascular and nonvascular patients. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01382862. The Pre-Hospital Acute Neurological Therapy and Optimization of Medical Care in Stroke Patients study (PHANTOM-S) was registered (NCT01382862). This sub-study was observational and not registered separately, therefore.

Prehospital Thrombolysis: A Manual from Berlin

In acute ischemic stroke, time from symptom onset to intervention is a decisive prognostic factor. In order to reduce this time, prehospital thrombolysis at the emergency site would be preferable. However, apart from neurological expertise and laboratory investigations a computed tomography (CT) scan is necessary to exclude hemorrhagic stroke prior to thrombolysis. Therefore, a specialized ambulance equipped with a CT scanner and point-of-care laboratory was designed and constructed. Further, a new stroke identifying interview algorithm was developed and implemented in the Berlin emergency medical services. Since February 2011 the identification of suspected stroke in the dispatch center of the Berlin Fire Brigade prompts the deployment of this ambulance, a stroke emergency mobile (STEMO). On arrival, a neurologist, experienced in stroke care and with additional training in emergency medicine, takes a neurological examination. If stroke is suspected a CT scan excludes intracranial hemorrhage. The CT-scans are telemetrically transmitted to the neuroradiologist on-call. If coagulation status of the patient is normal and patients medical history reveals no contraindication, prehospital thrombolysis is applied according to current guidelines (intravenous recombinant tissue plasminogen activator, iv rtPA, alteplase, Actilyse). Thereafter patients are transported to the nearest hospital with a certified stroke unit for further treatment and assessment of strokeaetiology. After a pilot-phase, weeks were randomized into blocks either with or without STEMO care. Primary end-point of this study is time from alarm to the initiation of thrombolysis. We hypothesized that alarm-to-treatment time can be reduced by at least 20 min compared to regular care.

Glial Fibrillary Acidic Protein for Prehospital Diagnosis of Intracerebral Hemorrhage

Background: Both, acute ischemic stroke (AIS) and hemorrhage stroke (intracerebral hemorrhage, ICH) require early attention but different treatment strategies. Plasma glial fibrillary acidic protein (GFAP) levels were found to be elevated in ICH patients after they arrived in the hospital. Because treatment options differed, we sought to determine whether GFAP can be used to accurately differentiate between of AIS and ICH in the prehospital setting. Methods: We assessed acute stroke patients in the Stroke Emergency Mobile (STEMO). STEMO is a stroke ambulance staffed by a specialized team including a neurologist and equipped with a computed tomography scanner plus a point-of-care laboratory. The STEMO ambulance is integrated in the emergency medical system of Berlin, Germany. Following prehospital stroke diagnosis, blood was drawn and subsequently analysed using research assays from Roche diagnostics. The clinical accuracy of plasma GFAP was tested using a cut-off value of 0.29 ng/ml. Results: Blood samples of 74 patients were analysed. Twenty-five patients had ICH (mean age 69 ± 11 years, median National Institutes of Health Stroke Scale (NIHSS) 15) and 49 IS (mean age 75 ± 10 years, median NIHSS 6). Nine ICH (0 IS patients) had GFAP-levels above 0.29 ng/ml. The sensitivity and specificity of GFAP for differentiating between ICH and AIS were 36.0 and 100%. The sensitivity for ICH volume >15 ml was 61.5%. ICH patients without GFAP elevation had significantly smaller hemorrhage volumes (median 4.5 vs. 37.6 ml, p = 0.004) and were less likely to deteriorate (19 vs. 56%, p = 0.087). Conclusions: GFAP levels >0.29 ng/ml were seen only in ICH, thus confirming the diagnosis of ICH during prehospital care. However, sensitivity is low particularly in smaller hemorrhages.

Influence of Distance to Scene on Time to Thrombolysis in a Specialized Stroke Ambulance

Background and Purpose— Specialized computed tomography–equipped stroke ambulances shorten time to intravenous thrombolysis in acute ischemic stroke by starting treatment before hospital arrival. Because of longer travel-time-to-scene, time benefits of this concept are expected to diminish with longer distances from base station to scene. Methods— We used data from the Prehospital Acute Neurological Treatment and Optimization of Medical Cares in Stroke (PHANTOM-S) trial comparing time intervals between patients for whom a specialized stroke ambulance (stroke emergency mobile) was deployed and patients with conventional emergency medical service. Expected times from base station to scene had been calculated beforehand using computer algorithms informed by emergency medical service routine data. Four different deployment zones with–75% probability–expected arrival within 4, 8, 12, and 16 minutes and total population coverage of ≈1.3 million inhabitants were categorized for stroke emergency mobile deployment. We analyzed times from alarm-to-arrival at scene, to start of intravenous thrombolysis and from onset-to-intravenous thrombolysis. Results— Corresponding to the size of the respective catchment zone, the number of patients cared increased with distance (zone 1: n=30, zone 2: n=127, zone 3: n=156, and zone 4: n=217). Although time to stroke emergency mobile arrival increased with distance (mean: 8.0, 12.5, 15.4, and 18.4 minutes in zones 1–4), time from alarm-to-intravenous thrombolysis (mean: 41.8 versus 76.5; 50.2 versus 79.1; 54.5 versus 76.6; and 59.3 versus 78.0 minutes, respectively; all P<0.01) remained shorter in the stroke emergency mobile group across all zones. Conclusions— In a metropolitan area such as Berlin, time benefits justify a specialized stroke ambulance service up to a mean travel time of 18 minutes from base station. Clinical Trial Registration— URL: https://www.clinicaltrials.gov. Unique identifier: NCT01382862.