S-100 protein and neuron-specific enolase concentrations in blood as indicators of infarction volume and prognosis in acute ischemic stroke

BACKGROUND AND PURPOSE

Better techniques are needed to monitor infarction volume and predict neurological outcome after ischemic brain infarction. We evaluated the usefulness of serial measurements of S-100 protein versus neuron-specific enolase (NSE) in blood samples from patients with acute stroke.

METHODS

Using nonisotopic sandwich immunoassays, we measured plasma concentrations of S-100 protein and NSE on admission and on days 3, 4, 7, and 14 after infarction in 44 patients (age range, 22 to 86 years; mean age, 65.1 years; 12 female, 32 male). Infarct volume was measured by volumetric CT on day 4 after ictus, and clinical outcome was assessed at discharge from hospital with the Activities of Daily Living Scale and 6 months after infarction with the Glasgow Outcome Scale.

RESULTS

Peak blood levels of S-100 protein were found on day 2.5 +/- 1.3, and peak levels of NSE were found on day 1.9 +/- 0.8 after infarction. Peak plasma levels of S-100 protein correlated well with infarct volume (r = .75, P < .001) and with clinical outcome assessed with the Glasgow Outcome Scale (r = .51, P < .001). Serum levels of NSE correlated with infarct volume (r = .37, P < .05) but not with clinical outcome (r = .18, P > .05).

CONCLUSIONS

The results of our study indicate that measuring blood concentrations of S-100 protein periodically in the first 10 days after cerebral infarction helps to predict infarct volume and the long-term neurological outcome more accurately than periodic measurements of blood concentrations of NSE.

Antithrombotic and Thrombolytic Therapy for Ischemic Stroke

This chapter about treatment and prevention of stroke is part of the 7th ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al). Among the key recommendations in this chapter are the following: For patients with acute ischemic stroke (AIS), we recommend administration of i.v. tissue plasminogen activator (tPA), if treatment is initiated within 3 h of clearly defined symptom onset (Grade 1A). For patients with extensive and clearly identifiable hypodensity on CT, we recommend against thrombolytic therapy (Grade 1B). For unselected patients with AIS of > 3 h but < 6 h, we suggest clinicians not use i.v. tPA (Grade 2A). For patients with AIS, we recommend against streptokinase (Grade 1A) and suggest clinicians not use full-dose anticoagulation with i.v. or subcutaneous heparins or heparinoids (Grade 2B). For patients with AIS who are not receiving thrombolysis, we recommend early aspirin therapy, 160 to 325 mg qd (Grade 1A). For AIS patients with restricted mobility, we recommend prophylactic low-dose subcutaneous heparin or low molecular weight heparins or heparinoids (Grade 1A); and for patients who have contraindications to anticoagulants, we recommend use of intermittent pneumatic compression devices or elastic stockings (Grade 1C). In patients with acute intracerebral hematoma, we recommend the initial use of intermittent pneumatic compression (Grade 1C+). In patients with noncardioembolic stroke or transient ischemic attack (TIA) [ie, atherothrombotic, lacunar or cryptogenic], we recommend treatment with an antiplatelet agent (Grade 1A) including aspirin, 50 to 325 mg qd; the combination of aspirin and extended-release dipyridamole, 25 mg/200 mg bid; or clopidogrel, 75 mg qd. In these patients, we suggest use of the combination of aspirin and extended-release dipyridamole, 25/200 mg bid, over aspirin (Grade 2A) and clopidogrel over aspirin (Grade 2B). For patients who are allergic to aspirin, we recommend clopidogrel (Grade 1C+). In patients with atrial fibrillation and a recent stroke or TIA, we recommend long-term oral anticoagulation (target international normalized ratio, 2.5; range, 2.0 to 3.0) [Grade 1A]. In patients with venous sinus thrombosis, we recommend unfractionated heparin (Grade 1B) or low molecular weight heparin (Grade 1B) over no anticoagulant therapy during the acute phase.

Markers of endothelial dysfunction in lacunar infarction and ischaemic leukoaraiosis

Patients with cerebral small vessel disease (SVD) can present as isolated lacunar infarction or with diffuse white matter changes, with the imaging appearance of leukoaraiosis. Endothelial dysfunction, which can lead to breakdown of the blood-brain barrier, impaired cerebral autoregulation and prothrombotic changes, is believed to be important in mediating disease. Circulating levels of intercellular adhesion molecule 1 (ICAM1), thrombomodulin (TM), tissue factor (TF) and tissue factor pathway inhibitor (TFPI) are markers of endothelial activation and damage, and may provide insights into disease pathogenesis or differences between phenotypes. We therefore measured these markers in a prospective series of patients with lacunar stroke. One hundred and ten white Caucasian patients with previous lacunar stroke and 50 community control subjects were studied. Markers of endothelial function were measured on venous blood samples. Patients were classified on brain imaging into two groups: isolated lacunar infarction (n = 47) and ischaemic leukoaraiosis, defined as a clinical lacunar stroke and leukoaraiosis on brain imaging (n = 63). The number of lacunes and severity of leukoaraiosis were also scored on MRI. ICAM1, TM and TFPI were elevated in cerebral SVD subjects compared with controls (P <or= 0.006). The ischaemic leukoaraiosis group had a different endothelial marker profile, with lower levels of TFPI (P = 0.01) and a higher TF/TFPI ratio (P = 0.01) compared with the isolated lacunar infarction group. TM levels were associated with the number of lacunes (P = 0.008) and the leukoaraiosis score (P = 0.03), but TF levels and the TF/TFPI ratio were associated only with the extent of leukoaraiosis (P <or= 0.02). These results suggest that there is evidence of chronic endothelial dysfunction in cerebral SVD, and endothelial prothrombotic changes may be important in mediating the ischaemic leukoaraiosis phenotype. Therapies which help to stabilize the endothelium may have a role in this group of patients.

What causes infarction in ischemic brain?: The Robert Wartenberg Lecture

Improved treatment of associated cardiovascular and hematogenous abnormalities has favorably influenced the incidence and outcome of cerebral vascular disease during the past 25 years. Strong evidence now indicates that attention to the carbohydrate content of the brain also may influence outcome from brain ischemia. With brain lactate levels above approximately 16 mmol per kilogram, ischemia produces tissue infarction; ie, the lesion includes astrocytic and endothelial necrosis as well as neuronal death. We find that equal degrees of ischemia accompanied by lower tissue lactate values produce only selective neuronal damage in predictably vulnerable areas; astrocytes and endothelia are spared and extracellular or progressive postischemic cerebral edema fails to develop. The findings suggest that astrocytes can function to defend brain tissue against the damaging effects of acute anoxia but that during such conditions, they are potentially vulnerable to high tissue lactate levels. Initial clinical evidence suggests that scrupulous attention to blood sugar may reduce the risk of human cerebral infarction after ischemia.

Lp(a) lipoprotein as a risk factor for coronary heart disease and cerebral infarction

Attempts were made to prepare antisera monospecific for Lp(a) lipoprotein and to investigate the distribution of subjects according to plasma levels of Lp(a) in Japanese controls and patients with coronary heart disease or cerebral infarction. Positive plasma reactions to the double diffusion test for Lp(a) (Ouchterlony) were observed in 32.3% of the healthy Japanese subjects, which is similar to results previously reported in western countries. The plasma threshold level of 17 mg/dl was considered an appropriate point for dividing subjects into positive and negative groups depending on reactions to the double diffusion test. When subjects were divided into two groups at 17 mg/dl, a significant association was found between a high plasma level of Lp(a) and either coronary heart disease or cerebral infarction in the distribution of the cortical artery. These results suggest that Lp(a) may play an important part as a risk factor for coronary heart disease and cerebral infarction.

17beta-estradiol reduces stroke injury in estrogen-deficient female animals

BACKGROUND AND PURPOSE

The importance of postmenopausal estrogen replacement therapy for stroke in females remains controversial. We previously showed that female rats sustain less infarction in reversible middle cerebral artery occlusion (MCAO) than their ovariectomized counterparts and that vascular mechanisms are partly responsible for improved tissue outcomes. Furthermore, exogenous estrogen strongly protects the male brain, even when administered in a single injection before MCAO injection. The present study examined the hypothesis that replacement of 17beta-estradiol to physiological levels improves stroke outcome in ovariectomized, estrogen-deficient female rats, acting through blood flow-mediated mechanisms.

METHODS

Age-matched, adult female Wistar rats were ovariectomized and treated with 0, 25, or 100 microgram of 17beta-estradiol administered through a subcutaneous implant or with a single Premarin (USP) injection (1 mg/kg) given immediately before ischemia was induced (n=10 per group). Each animal subsequently underwent 2 hours of MCAO by the intraluminal filament technique, followed by 22 hours of reperfusion. Ipsilateral parietal cortex perfusion was monitored by laser-Doppler flowmetry throughout ischemia. Cortical and caudate-putamen infarction volumes were determined by 2,3, 5-triphenyltetrazolium chloride staining and digital image analysis. End-ischemic regional cerebral blood flow was measured in ovariectomized females with 0- or 25-microgram implants (n=4 per group) by (14)C-iodoantipyrine quantitative autoradiography.

RESULTS

Plasma estradiol levels were 3.0+/-0.6, 20+/-8, and 46+/-10 pg/mL in the 0-, 25-, and 100-microgram groups, respectively. Caudate-putamen infarction (% of ipsilateral caudate-putamen) was reduced by long-term, 25-microgram estrogen treatment (13+/-4% versus 31+/-6% in the 0-microgram group, P<0.05, and 22+/-3% in the 100-microgram group). Similarly, cortical infarction (% of ipsilateral cortex) was reduced only in the 25-microgram group (3+/-2% versus 12+/-3% in the 0-microgram group, P<0.05, and 6+/-3% in the 100-microgram group. End-ischemic striatal or cortical blood flow was not altered by estrogen treatment at the neuroprotective dose. Infarction volume was unchanged by acute treatment before MCAO when estrogen-treated animals were compared with saline vehicle-treated animals.

CONCLUSIONS

Long-term estradiol replacement within a low physiological range ameliorates ischemic brain injury in previously ovariectomized female rats. The neuroprotective mechanism is flow-independent, not through preservation of residual ischemic regional cerebral blood flow. Furthermore, the therapeutic range is narrow, because the benefit of estrogen in transient vascular occlusion is diminished at larger doses, which yield high, but still physiologically relevant, plasma 17beta-estradiol levels. Lastly, unlike in the male brain, single-injection estrogen exposure does not salvage ischemic tissue in the female brain. Therefore, although exogenous steroid therapy protects both male and female estrogen-deficient brain, the mechanism may not be identical and depends on long-term hormone augmentation in the female.

Elevated platelet microparticles in transient ischemic attacks, lacunar infarcts, and multiinfarct dementias

Platelets release microparticles (PMP) upon activation. Elevated levels of PMP were observed in patients with immune thrombocytopenic purpura (ITP), sometimes associated with a syndrome resembling transient ischemic attack (TIA), suggesting a thrombogenic potential for PMP. To determine if this association applies to TIA and other cerebrovascular accidents (CVA) without ITP, we studied PMP profiles in 71 patients with ischemic CVA: 28 with small vessel CVA (SCVA), either lacunar infarcts or TIA; 24 with large vessel CVA (LCVA); 19 with multiinfarct dementia (MID); 12 with Alzheimer's dementia (AD); and 31 healthy controls. The mean PMP values were: MID = 3.71 +/- 0.51; SCVA = 3.48 +/- 0.63; LCVA = 1.97 +/- 0.28; AD = 1.19 +/- 0.27; controls = 0.88 +/- 0.09, (all units x 10(7)/mL). PMP values in all groups except AD were significantly above normal (p < 0.01). However, the elevation in SCVA was more marked than in LCVA (p < 0.01). Administration of the calcium channel blocker, nifedipine, to 11 TIA patients reduced PMP significantly.

Lateralization in autononic dysfunction in ischemic stroke involving the insular cortex

Autonomic nervous system dysfunction is a common complication of ischemic stroke. Clinical and experimental data indicate hemispheric lateralization in the control of autonomic activity. The insular cortex has also been shown to play a crucial role in the central autonomic network. The aim of this study was to assess cardio-autonomic dysfunction in patients with ischemic insular versus non-insular cortex infarction, and to demonstrate a possible lateralization in autonomic activity mediated by the insular cortex. Sympathetic function was prospectively assessed by determining plasma norepinephrine and epinephrine in 15 patients with left-hemisphere (LH; four insular infarction), and 14 with right-hemisphere (RH) middle cerebral artery (MCA) stroke (five insular infarction). Systolic and diastolic blood pressure and heart rate were recorded during the first 5 days after stroke. Sympathetic activity was significantly higher in insular than in non-insular infarction (p < 0.05) with concomitantly elevated cardiovascular parameters in insular stroke patients. The pathological activation of the sympathetic nervous system was most excessive in RH-stroke involving the insular cortex (p < 0.05). Our data indicate a hemispheric lateralization in autonomic activity which is mediated by the right-sided insular cortex. Patients with RH stroke involving the insular cortex are most susceptible to develop cardio-autonomic dysfunction.

Neuroanatomic correlates of stroke-related myocardial injury

BACKGROUND

Myocardial injury can occur after ischemic stroke in the absence of primary cardiac causes. The neuroanatomic basis of stroke-related myocardial injury is not well understood.

OBJECTIVE

To identify regions of brain infarction associated with myocardial injury using a method free of the bias of an a priori hypothesis as to any specific location.

METHODS

Of 738 consecutive patients with acute ischemic stroke, the authors identified 50 patients in whom serum cardiac troponin T (cTnT) elevation occurred in the absence of any apparent cause within 3 days of symptom onset. Fifty randomly selected, age- and sex-matched patients with ischemic stroke without cTnT elevation served as controls. Diffusion-weighted images with outlines of infarction were co-registered to a template, averaged, and then subtracted to find voxels that differed between the two groups. Voxel-wise p values were determined using a nonparametric permutation test to identify specific regions of infarction that were associated with cTnT elevation.

RESULTS

The study groups were well balanced with respect to stroke risk factors, history of coronary artery disease, infarction volume, and frequency of right and left middle cerebral artery territory involvement. Brain regions that were a priori associated with cTnT elevation included the right posterior, superior, and medial insula and the right inferior parietal lobule. Among patients with right middle cerebral artery infarction, the insular cluster was involved in 88% of patients with and 33% without cTnT elevation (odds ratio: 15.00; 95% CI: 2.65 to 84.79).

CONCLUSIONS

Infarctions in specific brain regions including the right insula are associated with elevated serum cardiac troponin T level indicative of myocardial injury.

Profiles of matrix metalloproteinases, their inhibitors, and laminin in stroke patients: influence of different therapies

BACKGROUND AND PURPOSE

The goal of this study was to determine the temporal profile of several matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs), and laminin (an MMP substrate) in human stroke under different treatment paradigms, including thrombolysis and hypothermia.

METHODS

We serially measured the serum levels of MMP-2, MMP-3, MMP-9, MMP-13, TIMP-1, TIMP-2, and laminin in 50 patients with acute ischemic stroke using zymography or enzyme-linked immunosorbent assay. Patients were treated with heparin, therapeutic thrombolysis, or hypothermia. Scandinavian Stroke Scale scores were obtained at baseline. Infarct volume was measured with CT scanning on day 4 after stroke onset. Healthy persons were used as control subjects.

RESULTS

MMP-2 and MMP-9 increased during the course of ischemia, whereas intact laminin and TIMP-2 decreased significantly (P<0.05). MMP-9 and laminin levels varied significantly by infarct size (P=0.001) and therapy (P=0.0005). MMP-9 levels were significantly higher in patients treated with tissue plasminogen activator (tPA) compared with patients treated with hypothermia. The cleaved form of MMP-9 was found solely in 4 patients treated with tPA. Intact laminin levels were significantly lower in the tPA group than in the hypothermia group.

CONCLUSIONS

Selected MMPs and TIMPs are involved in the pathophysiology of acute stroke. This is also reflected by changes in laminin. Treatment paradigms differentially influence levels of MMP-9 and laminin. Combination therapies explicitly involving MMP inhibition could be of value in future treatment strategies.

Neuroexcitatory amino acids and their relation to infarct size and neurological deficit in ischemic stroke

BACKGROUND AND PURPOSE

The participation of excitatory amino acids (EAAs) in the pathogenesis of ischemic neuronal lesion has been experimentally demonstrated, but clinical experience is scarce. Our objective was to examine EAA levels during the acute phase of cerebral infarction in relation to infarct size and intensity of neurological deficit.

METHODS

Using high-performance liquid chromatography, we determined the glutamate, aspartate, taurine, and glycine concentrations in the plasma and cerebrospinal fluid (CSF) of 128 patients with ischemic cerebral infarction confirmed by CT and 43 control subjects. Blood and CSF samples were obtained on admission within the first 24 hours from symptom onset. The severity of the neurological deficit was assessed with the Canadian Stroke Scale immediately after these tests and at 48 hours after inclusion in the study. Infarct volume was determined in a second CT performed between the 4th and 7th day after the patient's inclusion.

RESULTS

The concentration of plasmatic glutamate was 121.39 +/- 80.89 mumol/L in the control group and 163.71 +/- 103.13 mumol/L in the patient group (P = .015); in CSF it was 3.46 +/- 1.20 mumol/L in control subjects and 6.55 +/- 4.65 mumol/L in patients (P < .0001). The concentration of glycine in plasma was 158.02 +/- 32.15 mumol/L in control subjects and 189.37 +/- 74.04 mumol/L in patients (P = .007); in CSF it was 6.18 +/- 2.28 mumol/L in control subjects and 11.23 +/- 6.96 mumol/L in patients (P < .0001). The concentrations of glutamate in plasma and in CSF were significantly higher in patients with large cerebral infarcts and in those with cortical infarcts. Levels of glutamate and glycine in plasma and CSF were significantly higher in patients with a higher degree of neurological deficit.

CONCLUSIONS

Our results support the excitotoxic activity of glutamate and glycine in patients with cerebral infarction.

Prognostic relevance of pathological sympathetic activation after acute thromboembolic stroke

OBJECTIVE

To evaluate the prognostic impact of early pathologic sympathetic activation after stroke.

METHODS

The authors examined 112 consecutive patients (mean age, 69 years; 60 men) with their first brain infarction. A pathologic sympathetic activation was presumed if the initial norepinephrine level exceeds 300 pg/mL. In addition, involvement of the insular cortex, nighttime blood pressure changes, and several cardiovascular risk factors were determined. One-year outcome measures were mortality rate, cardiovascular and cerebrovascular events, and activities of daily living (Barthel index and Rankin score).

RESULTS

Norepinephrine levels greater than 300 pg/mL, nighttime blood pressure increases, and insular involvement were associated with a lower Barthel index (p < 0.005) at the 1-year follow-up. By stepwise logistic regression analysis, insular infarction, serum norepinephrine concentration, right-sided infarction, and nighttime blood pressure increase were significant and independent predictors of an unfavorable functional outcome. Cox regression analysis showed a higher rate of cardiovascular and cerebrovascular events (hazard ratio, 2.9; 95% CI, 1.07; 6.83; p < 0.04) in patients with initially increased norepinephrine concentrations.

CONCLUSIONS

The involvement of the insular cortex, the occurrence of a pathologic nighttime blood pressure increase, and an initially increased serum norepinephrine concentration are independent predictors of poor long-term outcome.

Cannabidiol Prevents Cerebral Infarction Via a Serotonergic 5-Hydroxytryptamine 1A Receptor–Dependent Mechanism

Background and Purpose— Cannabidiol has been reported to be a neuroprotectant, but the neuroprotective mechanism of cannabidiol remains unclear. We studied the neuroprotective mechanism of cannabidiol in 4-hour middle cerebral artery (MCA) occlusion mice.

Methods— Male MCA occluded mice were treated with cannabidiol, abnormal cannabidiol, anandamide, methanandamide, cannabidiol plus capsazepine, and cannabidiol plus WAY100135 before and 3 hours after MCA occlusion. The infarct size was determined after 24 hours (2,3,5-triphenyltetrazolium chloride staining). Cerebral blood flow (CBF) was measured at, before and 1, 2, 3, and 4 hours after MCA occlusion.

Results— Cannabidiol significantly reduced the infarct volume induced by MCA occlusion in a bell-shaped curve. Similarly, abnormal cannabidiol but not anandamide or methanandamide reduced the infarct volume. Moreover, the neuroprotective effect of cannabidiol was inhibited by WAY100135, a serotonin 5-hydroxytriptamine 1A (5-HT 1A ) receptor antagonist but not capsazepine a vanilloid receptor antagonist. Cannabidiol increased CBF to the cortex, and the CBF was partly inhibited by WAY100135 in mice subjected to MCA occlusion.

Conclusions— Cannabidiol and abnormal cannabidiol reduced the infarct volume. Furthermore, the neuroprotective effect of cannabidiol was inhibited by WAY100135 but not capsazepine, and the CBF increased by cannabidiol was partially reversed by WAY100135. These results suggested that the neuroprotective effect of cannabidiol may be related to the increase in CBF through the serotonergic 5-HT 1A receptor.

Delayed postischemic hyperthermia in awake rats worsens the histopathological outcome of transient focal cerebral ischemia

BACKGROUND AND PURPOSE

Over the past several years, it has been demonstrated that mild intraischemic or immediate postischemic hyperthermia worsens ischemic outcome in models of global and focal ischemia. Periods of hyperthermia are commonly seen in patients after stroke and cardiac arrest. The hypothesis tested in this study was that a brief hyperthermic period, even when occurring days after an ischemic insult, has detrimental effects on the pathological outcome of focal ischemia.

METHODS

Rats were subjected to 60 minutes of transient middle cerebral artery occlusion by insertion of an intraluminal filament. Twenty-four hours after reperfusion, awake rats were subjected to temperature modulation for 3 hours in a heating chamber. The brain temperature was equilibrated to either 37 degrees C to 38 degrees C, or 40 degrees C. Changes in rectal temperature and blood glucose concentration were evaluated during and just after temperature modulation. Behavioral tests were also assessed. Three days after temperature modulation, brains were perfusion-fixed, and infarct volumes were determined.

RESULTS

In animals with 40 degrees C hyperthermia, cortical and total infarct volumes were markedly greater (92.2 +/- 63.1 and 126.5 +/- 72.3 mm3 [mean +/- SD], respectively) than in normothermic rats (14.4 +/- 12.7 and 42.4 +/- 19.2 mm3) and in animals with 39 degrees C hyperthermia (16.5 +/- 28.7 and 40.9 +/- 34.3 mm3) (P < .05), whereas there was no significant difference between normothermic and 39 degrees C hyperthermic animals. In addition, animals with 40 degrees C hyperthermia displayed worsened neurological scores compared with normothermic and 39 degrees C hyperthermic rats. In the 39 degrees C hyperthermia group, rectal temperatures were significantly lower (by 0.2 degree C to 0.5 degree C) than brain temperatures throughout the modulation period.

CONCLUSIONS

The present findings provide evidence that, after a transient focal ischemic insult, the postischemic brain becomes abnormally sensitive to the effects of delayed temperature elevation, even of moderate degree. The threshold for aggravation of ischemic injury by delayed hyperthermia appears to be approximately 40 degrees C. Body-temperature measurements, in both awake and anesthetized animals, may not accurately reflect brain temperature under these conditions. The present study stresses that fever of even moderate degree in the days following brain ischemia may markedly exacerbate brain injury.

IL-6: an early marker for outcome in acute ischemic stroke

OBJECTIVES

Inflammation plays an important role in the pathophysiology of stroke. We correlated interleukin (IL)-6, IL-10, C-reactive protein (CRP) and T-lymphocyte subtype levels in acute ischemic stroke patients with stroke volume and clinical outcome.

MATERIALS AND METHODS

Blood samples were obtained from 11 patients at defined intervals during 1 year. Nine healthy age-matched subjects served as controls. IL-6, IL-10 and CRP were quantified by enzyme-linked immunosorbent assay and T lymphocytes by flow cytometry. Volume measurement was carried out by computed tomography or magnetic resonance imaging and clinical outcome was scored by the European stroke scale (ESS) and Barthel index (BI).

RESULTS

IL-6 levels were increased in the acute phase of stroke compared with healthy controls (P = 0.002) and correlated with larger stroke volume (P = 0.012) and less favorable prognosis after 1 year, measured by ESS (P = 0.014) and BI (P = 0.006). IL-10, CRP and T-lymphocyte subtypes in the acute phase were not correlated with stroke volume or clinical outcome.

CONCLUSION

IL-6 seems to be a robust early marker for outcome in acute ischemic stroke.

Pattern of activation of the hypothalamic-pituitary-adrenal axis in acute stroke. Relation to acute confusional state, extent of brain damage, and clinical outcome

BACKGROUND AND PURPOSE

The aim of this study was to characterize the response of the hypothalamic-pituitary-adrenal system in the first hours of ischemic stroke and to relate its extent to the occurrence of acute confusional state, volume of brain damage, and clinical outcome.

METHODS

The secretion of corticotropin (adrenocorticotropic hormone [ACTH]) and cortisol was studied in 23 patients by determinations at hours 4, 6, 8, 10, and 14 and days 1, 3, 5, and 7 after onset of symptoms. Acute confusional state (DSM-III-R criteria), extent of lesion (volumetry of computed tomographic scans), and neurological and functional outcome (Scandinavian Stroke Scale, Barthel Index scores) were assessed.

RESULTS

The massive neuroendocrine response observed consisted of an initial phase with concomitantly increased levels of ACTH and cortisol and a second phase with decreased levels of ACTH while high concentrations of cortisol persisted. Initial levels of ACTH but not cortisol were significantly increased in patients with acute confusional state and significantly correlated with volume of brain lesion and neurological and functional outcome.

CONCLUSIONS

An early and persisting activation of the hypothalamic-pituitary-adrenal axis was observed in relation to severity of disease. Its characteristic biphasic pattern suggests an initial central stimulation of release of ACTH followed by feedback suppression concomitant with an increased susceptibility of the adrenal gland. Because these hormones are known to exacerbate hypoxic injury to neurons, their massive release in hyperacute stroke may increase the extent of brain damage.

Increased plasma endothelin-1 in acute ischemic stroke

BACKGROUND AND PURPOSE

Endothelins are a recently discovered group of most powerful vasoconstrictor peptides. Endothelin-1 is produced by endothelial cells, and endothelin-3 is derived from neuronal tissue. Theoretically, endothelin-mediated vasoconstriction may enhance ischemic neuronal damage. This study aimed to measure plasma levels of both endothelins in patients with acute nonhemorrhagic cerebral infarction.

SUMMARY OF REPORT

Plasma levels of endothelin-1 and endothelin-3 were measured by radioimmunoassay in 16 consecutive patients within the first 72 hours after the onset of nonhemorrhagic cerebral infarct, as diagnosed clinically and by computed tomography. There was a marked (fourfold) elevation in plasma endothelin-1 levels in the patients (median, 11.7 pg/ml; 25th and 75th centiles, 5.4 and 13.2 pg/ml) compared with those in a control group of 13 age-matched subjects (median, 2.56 pg/ml; 25th and 75th centiles, 2.4 and 3.0 pg/ml; p less than 0.0001). The first 24 hours after stroke onset were associated with higher endothelin-1 levels, and there was a trend to elevated levels with more severe neurological deficits. In all patients and controls endothelin-3 levels were below 0.5 pg/ml.

CONCLUSIONS

Ischemic stroke is associated with acute and marked increases in plasma levels of endothelin-1. This may reflect enhanced production by damaged endothelial cells within the infarcted tissue. Local leakage of endothelin-1 may induce severe and prolonged constriction of collateral vessels and may therefore have a deleterious role in the pathogenesis and final outcome of cerebral infarction.

Whole blood viscosity parameters and cerebral blood flow

This report describes the statistical relationship of several whole blood viscosity parameters and cerebral blood flow (CBF) in 53 consecutive patients and normal controls. Significant correlations were present between CBF and serum fibrinogen (P = .05), hematocrit (P less than .05), and a relationship involving both fibrinogen and hematocrit (P less than .01). We conclude that heightened whole blood viscosity does correlate with decreased cerebral blood flow in the ranges measured in our patients, that both fibrinogen and hematocrit must be taken into consideration in viscosity determinations, and that changes in viscosity may have an important effect on CBF in regions of low flow.

Elevated levels of plasma homocyst(e)ine and asymmetric dimethylarginine in elderly patients with stroke

Cerebrovascular risk factors, including hypertension, smoking, diabetes mellitus, aging, dyslipidemia, and hyperhomocyst(e)inemia are linked to endothelial dysfunction. Endothelial-derived nitric oxide (NO) has inhibitory effects on key processes in atherothrombosis. Although asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase, is associated with atherosclerotic disease, there has been no report on association of ADMA with ischemic stroke. Here we investigated the relation of plasma ADMA, stroke, and homocyst(e)inemia in the elderly. Plasma ADMA and homocyst(e)ine concentration was determined using high-performance liquid chromatography and fluorescence detection. Patients with ischemic stroke had significantly higher concentrations of plasma ADMA than controls (1.85+/-1.32 vs. 0.93+/-0.32 micromol/l, P=0.0001). After adjustment for risk factors, elevated ADMA levels, above 90th percentile of normal controls (> or =1.43 micromol/l) was associated with stroke (OR=6.05, 95% CI; 2.77-13.3, P=0.02). ADMA plasma levels were positively correlated to homocyst(e)ine levels (r=0.43, P=0.01). Multiple logistic regression analysis revealed that hyperhomocyst(e)inemia (plasma homocyst(e)ine concentration > or =15.0 micromol/l) was a significant predictor of elevated ADMA level. Altogether, findings indicate that elevated ADMA concentrations are at increased risk for ischemic stroke in the elderly, and may account for increased risk of stroke in patients with hyperhomocyst(e)inemia.

Stroke topography and outcome in relation to hyperglycaemia and diabetes

In a prospective study to analyse stroke topography and outcome in diabetics and to determine the prognostic value of blood glucose and glycosylated haemoglobin estimation, we evaluated 176 patients with acute stroke. The patients were classified into four groups on the basis of history, fasting glucose, and glycosylated haemoglobin: euglycaemic patients with no history of diabetes, stress hyperglycaemia, newly diagnosed diabetics, and known diabetics. A high prevalence of undiagnosed diabetes was shown. No difference was found in the type or site of stroke between the four groups. No difference was found in the site of symptomatic or incidental lesions on computerised axial tomography. Patients with stress hyperglycaemia and known diabetics had more severe strokes. Mortality was higher in patients with stress hyperglycaemia, newly diagnosed diabetics, and the combined diabetes groups. This increased mortality was evident in the hyperglycaemic and diabetic groups, even after excluding patients with cerebral haemorrhage. Stroke severity and mortality also increased independently with blood glucose in the euglycaemic group. We conclude that there is a correlation between admission glucose concentration, diabetes, and poor stroke outcome, which may not be attributed to stroke type or location.

Different risk factors for different stroke subtypes: association of blood pressure, cholesterol, and antioxidants

BACKGROUND AND PURPOSE

Blood pressure is an important risk factor for stroke, but the roles of serum total and HDL cholesterol, alpha-tocopherol, and beta-carotene are poorly established. We studied these factors in relation to stroke subtypes.

METHODS

Male smokers (n=28 519) aged 50 to 69 years without a history of stroke participated in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, a controlled trial to test the effect of alpha-tocopherol and beta-carotene supplementation on cancer. From 1985 to 1993, a total of 1057 men suffered from primary stroke: 85 had subarachnoid hemorrhage; 112, intracerebral hemorrhage; 807, cerebral infarction; and 53, unspecified stroke.

RESULTS

Systolic blood pressure > or = 160 mm Hg increased the risk of all stroke subtypes 2.5 to 4-fold. Serum total cholesterol was inversely associated with the risk of intracerebral hemorrhage, whereas the risk of cerebral infarction was raised at concentrations > or = 7.0 mmol/L. The risks of subarachnoid hemorrhage and cerebral infarction were lowered with serum HDL cholesterol levels > or = 0.85 mmol/L. Pretrial high serum alpha-tocopherol decreased the risk of intracerebral hemorrhage by half and cerebral infarction by one third, whereas high serum beta-carotene doubled the risk of subarachnoid hemorrhage and decreased that of cerebral infarction by one fifth.

CONCLUSIONS

The risk factor profiles of stroke subtypes differ, reflecting different etiopathology. Because reducing atherosclerotic diseases, including ischemic stroke, by lowering high serum cholesterol is one of the main targets in public health care, further studies are needed to distinguish subjects with risk of hemorrhagic stroke. The performance of antioxidants needs confirmation from clinical trials.

Serum glial fibrillary acidic protein as a biomarker for intracerebral haemorrhage in patients with acute stroke

BACKGROUND

Biomarkers of stroke are an evolving field of clinical research. A serum marker which can differentiate between haemorrhagic and ischaemic stroke in the very early phase would help to optimise acute stroke management.

OBJECTIVE

To examine whether serum glial fibrillary acidic protein (GFAP) identifies intracerebral haemorrhage (ICH) in acute stroke patients.

METHODS

A pilot study assessing 135 stroke patients admitted within six hours after symptom onset. Diagnosis of ICH (n = 42) or ischaemic stroke (n = 93) was based on brain imaging. GFAP was determined from venous blood samples obtained immediately after admission, using a research immunoassay.

RESULTS

GFAP was detectable in the serum of 39 patients (34 of 42 (81%) with ICH, and five of 93 (5%) with ischaemic stroke). Serum GFAP was substantially raised in patients with ICH (median 11 ng/l, range 0 to 3096 ng/l) compared with patients with ischaemic stroke (median 0 ng/l, range 0 to 14 ng/l, p<0.001). Using receiver operating characteristic curve analysis, a cut off point of 2.9 ng/l provided a sensitivity of 0.79 and a specificity of 0.98 for the identification of ICH in acute stroke (positive predictive value 0.94, negative predictive value 0.91; p<0.001).

CONCLUSIONS

Serum GFAP can reliably detect ICH in the acute phase of stroke. Further evaluation of the usefulness of GFAP as an early diagnostic marker of ICH is now required, with the aim of optimising cause specific emergency management.

Plasma sulfhydryl-containing amino acids in patients with cerebral infarction and in hypertensive subjects

It has been postulated that an accumulation of a sulfhydryl-containing amino acid, homocysteine in plasma may induce arteriosclerosis. In order to explore a possible contribution of homocysteine to the development of cerebral infarction in middle-aged and elderly patients, plasma sulfhydryl-containing amino acid profiles of 45 patients with cerebral infarction (CI) were compared with those of 45 normotensive and 45 hypertensive controls, and 20 patients with cerebral bleeding (CB), of similar ages and sex. The concentrations of both free and total homocysteine in plasma were highest in patients with CI among the 4 groups, while plasma free and total cysteinylglycine levels were similar. Although both free and total cysteine levels were also higher in patients with CI than in normotensive controls, the total homocysteine/total cysteine ratio was highest in patients with CI among the four groups. The hypertensive controls had higher plasma free and total concentrations than normotensive controls, but the levels did not differ between the 21 normotensive and 24 hypertensive CI patients. Our results suggest that high levels of plasma homocysteine in conjunction with hypertension could be one of the risk factors for arteriosclerotic CI.

Circulating CD34-positive cells provide an index of cerebrovascular function

BACKGROUND

Increasing evidence points to a role for circulating endothelial progenitor cells, including populations of CD34- and CD133-positive cells present in peripheral blood, in maintenance of the vasculature and neovascularization. Immature populations, including CD34-positive cells, have been shown to contribute to vascular homeostasis, not only as a pool of endothelial progenitor cells but also as a source of growth/angiogenesis factors at ischemic loci. We hypothesized that diminished numbers of circulating immature cells might impair such physiological and reparative processes, potentially contributing to cerebrovascular dysfunction.

METHODS AND RESULTS

The level of circulating immature cells, CD34-, CD133-, CD117-, and CD135-positive cells, in patients with a history of atherothrombotic cerebral ischemic events was analyzed to assess possible correlations with the degree of carotid atherosclerosis and number of cerebral infarctions. There was a strong inverse correlation between numbers of circulating CD34- and CD133-positive cells and cerebral infarction. In contrast, there was no correlation between the degree of atherosclerosis and populations of circulating immature cells. Analysis of patients with cerebral artery occlusion revealed a significant positive correlation between circulating CD34- and CD133-positive cells and regional blood flow in areas of chronic hypoperfusion.

CONCLUSIONS

These results suggest a possible contribution of circulating CD34- and CD133-positive cells in maintenance of the cerebral circulation in settings of ischemic stress. Our data demonstrate the utility of a simple and precise method to quantify circulating CD34-positive cells, the latter providing a marker of cerebrovascular function.

Associations of serum total cholesterol, different types of stroke, and stenosis distribution of cerebral arteries. The Akita Pathology Study

BACKGROUND AND PURPOSE

The relation between serum total cholesterol levels and stroke is controversial. The Akita Pathology Study provides data on the association of serum total cholesterol, different types of stroke, and distribution of stenosis in cerebral arteries.

METHODS

The data are based on 750 autopsied men aged 30 years and older who were admitted to a local hospital in northeast Japan between 1966 and 1984. The overall autopsy rate was 88%. The grade of stenosis in the cerebral arteries was determined blindly by one pathologist using Baker's method for basal cerebral arteries (atherosclerosis scores) and using microscopic examination of a single basal ganglion slide for the intracerebral penetrating arteries (arteriolosclerosis scores).

RESULTS

The age-adjusted mean value of serum total cholesterol concentration was 164 mg/dL for cerebral hemorrhage, 177 mg/dL for infarction in penetrating artery regions, and 200 mg/dL for infarction in cortical artery regions. Mean serum cholesterol was lower in deaths caused by cerebral hemorrhage than in those caused by myocardial infarction and other cardiovascular disease. Mean atherosclerosis score of basal cerebral arteries was low for cerebral hemorrhage, intermediate for penetrating artery infarction, and high for cortical artery infarction. Stenosis of both basal and penetrating arteries was minimum or absent in cases of cerebral hemorrhage. Only the basal arteries were stenotic in cases of cortical artery infarction, whereas both basal and penetrating arteries were stenosed in cases of penetrating artery infarction. There were positive associations of serum cholesterol with stenosis of basal and penetrating arteries. Among cases of cerebral hemorrhage, serum total cholesterol levels were even lower in men with no significant stenosis in either basal or penetrating arteries than in men with stenosis in either type of artery.

CONCLUSIONS

The association of serum cholesterol with pathogenesis varies among stroke types. Elevated serum cholesterol levels were associated with the presence of cortical artery infarction, while low serum cholesterol levels were associated with cerebral hemorrhage.