Safety of Tirofiban in acute Ischemic Stroke: the SaTIS trial.

BACKGROUND AND PURPOSE: Tirofiban is a highly selective, fast-acting nonpeptide glycoprotein IIb/IIIa platelet receptor antagonist with a short half-life time. Glycoprotein IIb/IIIa antagonists are effective for the treatment of acute coronary syndromes proven in large clinical trials. Safety and efficacy in patients with ischemic stroke are uncertain. This was addressed in the Safety of Tirofiban in acute Ischemic Stroke (SaTIS) trial. METHODS: Two hundred sixty patients with acute ischemic stroke were randomized in a placebo-controlled, prospective, open-label treatment, blinded outcome reading multicenter trial. Subjects with a National Institutes of Health Stroke Scale between 4 and 18 received intravenously either tirofiban or placebo within 3 to 22 hours after symptom onset for 48 hours. The primary end point was the rate of cerebral bleeding as measured in follow-up CT scans 2 to 7 days after inclusion. The secondary end point was clinical efficacy within 1 week (National Institutes of Health Stroke Scale, modified Rankin Scale) and after 5 months (Barthel Index, modified Rankin Scale). RESULTS: The rate of cerebral hemorrhagic transformation (I/II) and parenchymal hemorrhage (I/II) did not differ between both groups (tirofiban 36 of 120; placebo 33 of 124: OR, 1.18; 95% CI, 0.66 to 2.06). Mortality after 5 months was significantly lower in patients treated with tirofiban (3 of 130 [2.3%] versus 11 of 126 [8.7%]; OR, 4.05; 95% CI, 1.1 to 14.9). No difference in neurological/functional outcome was found after 1 week and after 5 months. CONCLUSIONS: We conclude that tirofiban might be safe in acute moderate ischemic stroke even when administered within a large time window after symptom onset and might save lives in the late outcome. Clinical Trial Registration- URL: www.strokecenter.org/trials/. Trial name: SaTIS. Enrollment began before July 1, 2005.

[Imaging in cerebrovascular atherosclerotic disease]. / Bildgebung bei zerebrovaskulärer Erkrankung.

Brain imaging is one of the important diagnostic tool to elucidate cerebrovascular diseases. The common clinical routine is based on the technique of brain imaging by computed tomography (CT) or magnetic resonance (MR) and the imaging of the arterial vessels by means of ultrasound, CT angiography (CTA), or magnetic resonance angiography (MRA). Important information is obtained about type and pattern of brain lesions, perfusion of the brain, status of the vessels as well as the vessel wall. All tools are complementary and redundant techniques having advantages and disadvantages. The need for the gold standard - selective intraarterial angiography - is more and more limited to therapeutic interventions like angioplasty or local thrombolysis. MRI spectroscopy as well as diffusion tensor imaging provide new perspectives in the diagnosis of atherosclerotic brain lesions.

Variable platelet response to aspirin in patients with ischemic stroke.

BACKGROUND: A large number of patients experience ischemic stroke despite treatment with aspirin (acetylsalicylic acid, ASA). It is not clear whether all of these patients with ischemic stroke respond normally to ASA or are hyporesponsive as assessed by inhibition of aggregation and thromboxane (TX) synthesis. METHODS: We studied the effect of ASA given orally and ASA in vitro on collagen- and arachidonic-acid-induced TX formation and aggregation in platelet-rich plasma of 90 patients with ischemic stroke and 25 healthy control subjects. RESULTS: Thirty-seven patients were being treated with ASA at the time of stroke. Arachidonic-acid-induced TX formation was not depressed below a predefined threshold of 25 ng/ml in 9 patients. Eight of these however exhibited a normal platelet sensitivity to ASA in vitro, suggesting poor compliance or a pharmacokinetic mechanism of nonresponse. The addition of ASA in vitro did not inhibit arachidonic-acid-induced TX formation below the above threshold in 6 patients (11%) in the group of 53 stroke patients not receiving oral ASA, indicating an impaired response to ASA at the platelet level. Moreover, platelets from stroke patients showed an increased collagen-induced, TX-independent aggregation as compared with those of healthy individuals. CONCLUSION: Different categories of ASA nonresponders can be distinguished in patients with ischemic stroke. These include patients with poor bioavailability or noncompliance, an impaired platelet response to ASA in vitro and an increased, TX-independent hyperreactivity to collagen.

Aldolase C/zebrin II is released to the extracellular space after stroke and inhibits the network activity of cortical neurons.

Cell death after stroke involves apoptotic, autophagocytic and necrotic mechanisms which may cause the release of cytosolic proteins to the extracellular space. Aldolase C (AldC) is the brain specific isoform of the glycolytic enzyme fructose-1,6-bisphosphate aldolase. According to its characteristic striped expression pattern in the adult cerebellum AldC is also termed zebrin II. Here, we demonstrate release of AldC into the cerebrospinal fluid (CSF) after stroke in vivo. Studies with cell cultures confirmed that AldC is released to the extracellular space after hypoxia. Moreover, addition of purified recombinant AldC to networks of cortical neurons plated on multielectrode arrays reversibly inhibited the spontaneous generation of action potentials at AldC concentrations which can be expected to occur after lesions of the human cerebral cortex. This mechanism could be relevant in the pathogenesis of the electrophysiological changes in the penumbra region after stroke.

EUS-guided alcohol ablation of an insulinoma.

BACKGROUND: Surgical resection is currently considered to be the criterion standard for treatment of insulinomas. Alternative treatments, despite medication with diazoxide, are lacking. EUS-guided ethanol ablation of endocrine tumors has not been reported before. INTERVENTION: A 78-year-old woman was referred with typical symptoms of an insulinoma. Diagnosis was confirmed by laboratory findings, EUS, and EUS-guided FNA. Because of severe complications during several hypoglycemic episodes, a poor general condition, and strict refusal of surgical resection, the decision was made to ablate the insulinoma by EUS-guided alcohol injection. A total of 8 mL 95% ethanol was injected into the tumor. RESULTS: The patient was discharged and exhibited no further hypoglycemic episodes, and her general condition improved rapidly. Based on clinical, morphologic, and biochemical criteria, we achieved a durable complete remission of the tumor. CONCLUSIONS: EUS-guided ablation may become a minimally invasive alternative for patients with insulinomas in whom surgery is not feasible.

Initial ischemic event: perfusion-weighted MR imaging and apparent diffusion coefficient for stroke evolution.

PURPOSE: To prospectively determine if the degree of acute perfusion or diffusion abnormalities measured prior to treatment onset help predict the evolution of brain infarction on magnetic resonance (MR) images. MATERIALS AND METHODS: Local ethics committee approval and informed consent were obtained. On parametric maps obtained in 64 patients (mean age, 64 years +/- 13 [standard deviation]; 37 men and 27 women) with acute middle cerebral artery infarction, lesion volumetry was performed to determine time to peak, mean transit time, cerebral blood volume, and apparent diffusion coefficient obtained within 3 hours of symptom onset. The infarct lesions were assessed on T2-weighted MR images obtained at follow-up on day 8. Cerebrovascular changes were determined on MR angiograms. Inferential and correlation statistics were used. RESULTS: A perfusion delay of more than 6 seconds relative to the nonaffected hemisphere on time-to-peak maps helped to predict the lesion volume on T2-weighted images (r = 0.686, P < .001). In contrast, neither the volume nor the degree of the diffusion abnormality helped to predict the infarct volume (r < 0.46). This was because in one subgroup of patients there was an increase and in one subgroup there was a decrease in infarct volume on the T2-weighted images (P < .001). There was a greater prevalence (P < .02) of cerebral artery abnormalities in the patients with larger infarcts. Clinically, the neurologic impairment was more severe (P < .01) and the mean arterial pressure higher (P < .04) in these patients. CONCLUSION: The results suggest that in acute stroke the severity of the initial ischemic event as determined on time-to-peak maps indicates hemodynamic compromise in addition to internal carotid artery or middle cerebral artery occlusion, because of abnormalities in other cerebral arteries.

Partial rescue of the perfusion deficit area by thrombolysis.

PURPOSE: To investigate the evolution of the perfusion deficit area following systemic thrombolysis with recombinant tissue plasminogen activator (rtPA) in a clinical study on acute cerebral ischemia. MATERIALS AND METHODS: We performed volumetric measurements of the acute ischemic lesions in MR images of perfusion (TTP, MTT, and rCBV) and in diffusion-weighted (DW) images, as well as the manifest stroke lesions in T2-weighted MR images on day 8. We compared the data of 29 patients who were subjected to systemic thrombolysis with those of 18 patients who were not eligible for thrombolysis. RESULTS: In the treated patients there were prominent MTT/DWI and TTP/DWI mismatches (P < 0.0006). The acute TTP volumes were smaller than the acute MTT volumes, but as large as the T2 lesions on day 8. The MTT/T2 lesion volume reduction was significant (P < 0.03) in patients who received the GPIIb/IIIa receptor antagonist tirofiban (N = 13) in addition to the low-dose rtPA. This corresponded to a greater neurological improvement compared to patients who received rtPA alone (P < 0.05). In contrast, in the nontreated patients the initial MTT and TTP lesion volumes were of similar magnitude and predicted the T2 lesions on day 8. In the treated and nontreated patients the TTP lesion signified the viability threshold of acute ischemia, which corresponded to a rCBF of 25 +/- 11 mL/100 g/min. CONCLUSION: The perfusion deficit area comprises the ischemic core that is destined to undergo necrosis, and an ischemic rim that is salvageable by systemic thrombolysis.

Systemic thrombolysis with recombinant tissue plasminogen activator and tirofiban in acute middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: In acute ischemic stroke, thrombolytic treatment with recombinant tissue plasminogen activator (rtPA) is limited by a concomitant activation of the coagulatory system, leading to incomplete or delayed reperfusion, microcirculatory disturbances, or even repeated vessel occlusions. Our pilot study sought to assess the therapeutic potential of a new treatment strategy combining rtPA at reduced dosages with a platelet glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitory agent in acute middle cerebral artery occlusion. METHODS: Nineteen patients suffering from acute middle cerebral artery occlusion (Thrombolysis in Myocardial Infarction [TIMI] flow grade 0 to 1) underwent combined intravenous thrombolytic treatment using rtPA at reduced dosages and the GPIIb/IIIa antagonist tirofiban. Stroke MRI (diffusion- and perfusion-weighted imaging) and MR angiography were performed at baseline and between days 1 and 2 after treatment. Clinical scores (National Institutes of Health Stroke Scale and modified Rankin Scale) were assessed at baseline and after 1 week. RESULTS: Middle cerebral artery recanalization (TIMI flow grade 2 and 3) occurred in 13 of 19 patients (68%). The ischemic lesion on follow-up MRI was significantly smaller in patients with recanalization compared with those without recanalization (P=0.001). Only patients with recanalization improved neurologically (P<0.001). Because no symptomatic hemorrhage was observed, the power of our study to detect a symptomatic bleeding rate of > or =8% was at least 80%. CONCLUSIONS: Combined thrombolysis with a GPIIb/IIIa antagonist and rtPA at reduced dosages is promising but cannot be recommended for general use before prospective randomized clinical trials are completed.

Thrombolysis with recombinant tissue plasminogen activator and tirofiban in stroke: preliminary observations.

BACKGROUND AND PURPOSE: We sought to investigate the feasibility of the combined use of low-dose recombinant tissue plasminogen activator (rtPA) and tirofiban, a glycoprotein IIb/IIIa (GPIIb/IIIa) receptor antagonist, for systemic thrombolysis in acute stroke. METHODS: Consecutive patients who were treated with systemic application of low-dose rtPA and body weight-adjusted tirofiban (rtPA+T group; n=37) were evaluated retrospectively during 1999-2001. Patients in the rtPA+T group were compared with a group of patients treated with a dose of 0.9 mg/kg body weight in a different center (rtPA group; n=119). The 41 patients with infarctions of the middle cerebral artery territory who were not eligible for thrombolytic treatment because of medical contraindications or arrival in the hospital >3 hours after stroke onset served as controls. For matched comparisons, the National Institutes of Health Stroke Scale on admission and the Rankin Scale on discharge 5 days after stroke were used. RESULTS: The patients treated with rtPA+T or rtPA improved (P<0.05) compared with the controls at discharge; patients in the rtPA+T and rtPA groups reached a Rankin Scale score of 0 to 2 in 63% and 55%, respectively, while only 16% of the controls achieved this score. Death rates (8% in rtPA+T group and 5% in rtPA group) were similar among the 2 treatment groups. They included 1 fatal hemorrhage in the rtPA+T group and 4 fatal hemorrhages in the rtPA group. Five percent of the untreated patients developed symptomatic, nonfatal cerebral hemorrhage. CONCLUSIONS: Systemic combined thrombolysis with rtPA+T seems to be a feasible treatment in acute stroke.

Cerebral microembolism is blocked by tirofiban, a selective nonpeptide platelet glycoprotein IIb/IIIa receptor antagonist.

BACKGROUND: Microembolic signals (MES) as detected by transcranial Doppler ultrasound define an individual stroke risk in patients with carotid artery disease. To study the composition of MES in vivo, we used the glycoprotein IIb/IIIa (GPIIb/IIIa) receptor antagonist tirofiban, a highly selective platelet aggregation inhibitor. METHODS AND RESULTS: Twenty-four patients with recent cerebral or retinal embolism of arterial origin and a MES rate >6 per hour on initial transcranial Doppler ultrasonography recording received the short-acting GPIIb/IIIa antagonist tirofiban. With tirofiban, the MES rate dropped from a median (range) of 38 (9 to 324) to zero in all patients. After cessation of infusion, the inhibitory effect of tirofiban was reversible, with a significant increase of MES (median 13.5; range, 0 to 35; n=16; P=0.001). Six patients received overlapping oral antiplatelet agents and remained MES-negative. CONCLUSIONS: Cerebral microembolism of arterial origin has the property of solid emboli, with platelet-fibrinogen units as predominant constituent parts. GPIIb/IIIa antagonists may have the potential to bridge the ischemic risk in patients with unstable carotid disease.

Subcellular localization of collapsin response mediator proteins to lipid rafts.

Collapsin response mediator proteins (CRMPs) are involved in signal transduction after exposure of neural cells to the axon guidance molecule Semaphorin 3A/collapsin. All five known CRMPs are expressed in the developing cerebral cortex and neocortical neurons are responsive to Semaphorin 3A. Here, we examine the expression and subcellular localization of CRMPs in neocortical neurons and in neonatal rat brain. In neocortical neurons CRMP-4 was detected in the perikaryon with a diffuse cytosolic distribution. In neurites and at growth cones punctate staining patterns were observed. Extraction of neuron cultures with methyl-beta-cyclodextrin to deplete cholesterol caused rapid redistribution of the punctate CRMP-4 staining into larger patches and abundant growth cone collapse. Western blotting of brain extracts demonstrated for all CRMPs the existence of soluble, detergent-extractable, and Triton X-100-resistant forms. Furthermore, sucrose density gradient centrifugation after solubilization of brain membranes with Triton X-100 revealed that CRMP-1, -3, -5, and to a lower extent CRMP-4 are associated with a detergent-resistant fraction with low buoyant density, but CRMP-2 was not detectable in this fraction. Thus, we propose that lipid rafts form sites for the compartmentalization of signaling events involving specific CRMPs and that the integrity of these membrane microdomains is essential for the maintenance of growth cones.

Collapsin response mediator proteins of neonatal rat brain interact with chondroitin sulfate.

Chondroitin sulfate proteoglycans are structurally and functionally important components of the extracellular matrix of the central nervous system. Their expression in the developing mammalian brain is precisely regulated, and cell culture experiments implicate these proteoglycans in the control of cell adhesion, neuron migration, neurite formation, neuronal polarization, and neuron survival. Here, we report that a monoclonal antibody against chondroitin sulfate-binding proteins from neonatal rat brain recognizes collapsin response mediator protein-4 (CRMP-4), which belongs to a family of proteins involved in collapsin/semaphorin 3A signaling. Soluble CRMPs from neonatal rat brain bound to chondroitin sulfate affinity columns, and CRMP-specific antisera co-precipitated chondroitin sulfate. Moreover, chondroitin sulfate and CRMP-4 were found to be localized immuno-histochemically in overlapping distributions in the marginal zone and the subplate of the cerebral cortex. CRMPs are released to culture supernatants of NTera-2 precursor cells and of neocortical neurons after cell death, and CRMP-4 is strongly expressed in the upper cortical plate of neonatal rat where cell death is abundant. Therefore, naturally occurring cell death is a plausible mechanism that targets CRMPs to the extracellular matrix at certain stages of development. In summary, our data indicate that CRMPs, in addition to their role as cytosolic signal transduction molecules, may subserve as yet unknown functions in the developing brain as ligands of the extracellular matrix.

A monoclonal antibody against a neuron-specific 65-kDa protein with laminar expression in the developing cerebral cortex.

The extracellular matrix component chondroitin sulfate supports the survival of neocortical neurons and influences their differentiation in culture. During development of the rat forebrain expression of chondroitin sulfate peaks at around birth. To elucidate functional partners of this important player of neurogenesis, a monoclonal antibody, termed MAb-9, was generated after immunization with chondroitin sulfate-binding proteins from neonatal rat brain. In western blots of neonatal tissue, MAb-9 recognized a major brain-specific 65-kDa protein band. While most of the 65-kDa protein was present in the soluble compartment, a significant fraction was membrane-associated. Prolonged extraction of brain membranes with CHAPS revealed three additional minor protein bands of approximately 48, 50, and 58 kDa. Of these, the 50-kDa protein specifically bound to chondroitin sulfate C-Sepharose. Immunocytochemical studies and western blot analyses of cultures of neocortical neurons and astrocytes demonstrated that MAb-9 recognizes a neuron-specific cytosolic protein. In the developing cerebral cortex the protein was detectable by immunohistochemistry in the preplate and ventricular zones as early as embryonic day 15. On embryonic day 18, the protein was found in the marginal zone and the subplate, but it was not present in the emerging cortical plate. At the neonatal stage the immunoreactivity was distributed throughout the cerebral cortex with prominent staining of the marginal zone. A similar pattern was observed in the adult animal. Notably, the laminar distribution of MAb-9 immunoreactivity in the cerebral cortex during the prenatal period closely resembled the expression pattern reported for chondroitin sulfate. Thus, MAb-9 recognizes a neuronal cytosolic protein which might participate in neurotrophic signaling events triggered by chondroitin sulfate.