Precipitants of brain infarction. Roles of preceding infection/inflammation and recent psychological stress

New Directions in Infection-Associated Ischemic Stroke

The relationship between infections and stroke has not been fully characterized, probably delaying the development of specific treatments. This narrative review addresses mechanisms of stroke linked to infections, including hypercoagulability, endothelial dysfunction, vasculitis, and impaired thrombolysis. SARS-CoV-2, the virus that causes COVID-19, may promote the development of stroke, which may represent its most severe neurological complication. The development of specific therapies for infection-associated stroke remains a profound challenge. Perhaps the most important remaining issue is the distinction between infections that trigger a stroke versus infections that are truly incidental. This distinction likely requires the establishment of appropriate biomarkers, candidates of which are elevated levels of fibrin D-dimer and anticardiolipin/antiphospholipid antibodies. These candidate biomarkers might have potential use in identifying pathogenic infections preceding stroke, which is a precursor to establishing specific therapies for this syndrome.

A multi-granularity convolutional neural network model with temporal information and attention mechanism for efficient diabetes medical cost prediction

As the cost of diabetes treatment continues to grow, it is critical to accurately predict the medical costs of diabetes. Most medical cost studies based on convolutional neural networks (CNNs) ignore the importance of multi-granularity information of medical concepts and time interval characteristics of patients' multiple visit sequences, which reflect the frequency of patient visits and the severity of the disease. Therefore, this paper proposes a new end-to-end deep neural network structure, MST-CNN, for medical cost prediction. The MST-CNN model improves the representation quality of medical concepts by constructing a multi-granularity embedding model of medical concepts and incorporates a time interval vector to accurately measure the frequency of patient visits and form an accurate representation of medical events. Moreover, the MST-CNN model integrates a channel attention mechanism to adaptively adjust the channel weights to focus on significant medical features. The MST-CNN model systematically addresses the problem of deep learning models for temporal data representation. A case study and three comparative experiments are conducted using data collected from Pingjiang County. Through experiments, the methods used in the proposed model are analyzed, and the super contribution of the model performance is demonstrated.

Antecedent febrile illness and occurrence of stroke in West Africa: The SIREN study

BACKGROUND

Acute infections have been posited as potential precipitants or triggers of the occurrence of stroke among adults with traditional vascular risk factors. We evaluated associations between stroke occurrence and reported febrile illness within 4 weeks (potential antecedent infections) among West Africans.

METHODS

The Stroke Investigative Research and Educational Network (SIREN) is a multicenter, case-control study involving 15 sites in Ghana and Nigeria. Cases include adults aged ≥18 years with radiologically confirmed strokes. Controls were stroke-free adults matched with cased by age, gender and ethnicity. Detailed evaluations for vascular, lifestyle and psychosocial factors were performed. Participants were asked for evidence of any febrile illness within the past 4 weeks. We used conditional logistic regression to estimate adjusted odds ratios (aOR) with 95% Confidence Interval.

RESULTS

Among 3588 stroke cases recruited in Ghana and Nigeria between August 2014 and July 2018, 363 cases (10.1%) reported having a febrile illness within the 4 weeks prior to stroke occurrence. Having an antecedent infection was associated with stroke occurrence with an unadjusted OR of 1.19 (1.00-1.51) but aOR of 0.83 (0.59-1.17) upon adjusting for traditional vascular risk factors. Stress, aOR of 4.69 (2.59-8.50) and consumption of green vegetables 2.27 (1.35-2.85) were associated with antecedent febrile illness.

CONCLUSION

1 in 10 stroke cases reported antecedent history of febrile illness prior to occurrence of stroke but no independent association was observed in this study. Infectious exposures may be important triggers of cardiovascular events requiring further exploratory studies to better understand the role of this emerging risk factor.

Acute Psychological Stress is a Trigger for Stroke: A Case-Crossover Study

BACKGROUND

Conventional risk factors for stroke that have been identified are mostly chronic diseases that explain much of the variation as to who develops stroke. However, these risk factors do not equip us with the means to predict when an event like stroke will occur. It has been observed that acute events like stroke and coronary heart disease are preceded by episodes of acute stress. The present study was undertaken to determine whether acute psychological stress is a potential triggering factor for the occurrence of stroke.

METHODS

In accordance with the case-crossover study design, patients or Legally Authorized Representative (LAR) were asked to report psychological stress during the two-hour hazard period before the event and during the control period, which was the same 2-hour time period the day before the event. Conditional logistic regression was used to compare each person's exposure during the hazard period to their exposure during the control period.

RESULTS

A total of 151 stroke patients were interviewed. Acute psychological stress was associated with transient increased odds of stroke in the subsequent 2 hours that was 3.4 times higher than the odds during periods with no exposure to these triggers (95% confidence interval 1.55-7.50).

CONCLUSIONS

Acute psychological stress is a potential independent triggering factor for the occurrence of stroke. Further confirmatory studies are required to help corroborate these findings and elucidate the mechanisms underlying this short-term increase in risk.

The relation of oxidative stress and apoptosis to histopathologic alterations in the lungs as a result of global cerebral ischemia

Heart attack and oxygen deficiency may cause necrosis in the brain and other tissues. We investigated the histopathological effects of nitric oxide (NO) on ischemia/reperfusion in lung and hippocampus using a rat brain bilateral occlusion ischemia model. Male rats were assigned to sham (SH), ischemic preconditioning (PC), global ischemia (GI) and ischemic reperfusion (IR) groups. Before ischemia was induced, blood was drawn to induce hypovolemic hypotension and for blood gas testing. After sacrifice, samples of hippocampus were harvested. Sections were examined using hematoxylin and eosin (H & E) staining and immunostaining using primary antibodies for GFAP, S100β, iNOS, eNOS and the TUNEL method. Following ischemia, we found evidence of gliosis induced oxidative stress and apoptosis in the hippocampus. No significant differences were detected between the SH and PC groups. In the GI and IR groups, apoptosis and necrosis were observed in the hippocampus. Lung sections were stained with H & E and Masson's trichrome (MT) and immunostained for iNOS and eNOS. The TUNEL method was used to detect apoptosis. Interstitial edema, vascular congestion, intra-alveolar hemorrhage, perivascular edema, neutrophil infiltration and disruption of alveoli were observed after global ischemia and ischemic reperfusion. Inflammatory cells were detected in the connective tissue. The IR and GI groups exhibited significantly more apoptotic cells than the SH or PC groups. Free radicals, such as nitric oxide (NO), that appear following ischemia and reperfusion in the brain may also injure the lungs. Increased NO in both lung and brain tissue suggests that apoptosis in these organs can be induced by reactive nitrogen species.

Newly recognized cerebral infarctions on postmortem imaging: a report of three cases with systemic infectious disease

BACKGROUND

Postmortem imaging (PMI) refers to the imaging of cadavers by computed tomography (CT) and/or magnetic resonance imaging (MRI). Three cases of cerebral infarctions that were not found during life but were newly recognized on PMI and were associated with severe systemic infections are presented.

CASE PRESENTATIONS

An 81-year-old woman with a pacemaker and slightly impaired liver function presented with fever. Imaging suggested interstitial pneumonia and an iliopsoas abscess, and blood tests showed liver dysfunction and disseminated intravascular coagulation (DIC). Despite three-agent combined therapy for tuberculosis, she died 32 days after hospitalization. PMI showed multiple fresh cerebral and cerebellar infarctions and diffuse ground-glass shadows in bilateral lungs. On autopsy, the diagnosis of miliary tuberculosis was made, and non-bacterial thrombotic endocarditis that involved the aortic valve may have caused the cerebral infarctions. A 74-year-old man on steroid therapy for systemic lupus erythematosus presented with severe anemia, melena with no obvious source, and DIC. Imaging suggested intestinal perforation. The patient was treated with antibiotics and drainage of ascites. However, he developed adult respiratory distress syndrome, worsening DIC, and renal dysfunction and died 2 months after admission. PMI showed infiltrative lung shadow, ascites, an abdominal aortic aneurysm, a wide infarction in the right parietal lobe, and multiple new cerebral infarctions. Autopsy examination showed purulent ascites, diffuse peritonitis, invasive bronchopulmonary aspergillosis, and non-bacterial thrombotic endocarditis that likely caused the cerebral infarctions. A 65-year-old man with an old pontine infarction presented with a fever and neutropenia. Despite appropriate treatment, his fever persisted. CT showed bilateral upper lobe pneumonia, pain appeared in both femoral regions, and intramuscular abscesses of both shoulders developed. His pneumonia worsened, his level of consciousness decreased, right hemiplegia developed, and he died. PMI showed a newly diagnosed cerebral infarction in the left parietal lobe. The autopsy revealed bilateral bronchopneumonia, right-sided pleuritis with effusion, an intramuscular abscess in the right thigh, and fresh multiple organ infarctions. Systemic fibrin thrombosis and DIC were also found. Postmortem cultures showed E. coli and Burkholderia cepacia.

CONCLUSION

Cerebral infarction that is newly recognized on PMI might suggest the presence of severe systemic infection.

Association between insufficient medication of antihypertensives and the severity of acute ischemic stroke

Background

Although recent studies have suggested that adherence to antihypertensive treatment reduced stroke incidence, the relationship of adherence to antihypertensives with stroke severity has not been studied. This study attempted to know whether nonadherence before stroke is associated with initial severity of acute ischemic stroke.

Methods

Consecutive patients with acute ischemic stroke were identified in Soonchunhyang University Hospital from Mar 2005 to Aug 2014, excluding the cases without hypertension or information of antihypertensive adherence. We compared the mean of National Institute of Health Stroke Scale (NIHSS) score between adherence groups and insufficient medication group, and additionally in each stroke subtype. Multiple linear regression model was established for initial NIHSS score adjusting alleged factors linked to stroke severity.

Results

Initial NIHSS score were higher in insufficient medication group than adherence group (6.5 ± 7.2 VS 5.4 ± 5.7, P = .11). In large artery atherosclerosis (LAA) and small vessel occlusion (SVO), initial NIHSS score were significantly higher in insufficient medication group (6.1 ± 6.5 VS 4.4 ± 4.4, P = .004 for LAA; 3.8 ± 3.5 VS 2.7 ± 1.8, P = .014 for SVO). In multiple linear regression model, insufficient medication to antihypertensives had a significant effect on NIHSS score (t = 3.417, P = .001) after adjusting covariates.

Conclusion

Insufficient medication of antihypertensives before stroke was independently associated with the severity of acute ischemic stroke. Further studies with prospective designs are warranted to evaluate clinical implication of adherence to antihypertensives for ischemic stroke.

Infection, vaccination, and childhood arterial ischemic stroke: Results of the VIPS study

OBJECTIVES

Minor infection can trigger adult arterial ischemic stroke (AIS) and is common in childhood. We tested the hypotheses that infection transiently increases risk of AIS in children, regardless of stroke subtype, while vaccination against infection is protective.

METHODS

The Vascular Effects of Infection in Pediatric Stroke study is an international case-control study that prospectively enrolled 355 centrally confirmed cases of AIS (29 days-18 years old) and 354 stroke-free controls. To determine prior exposure to infections and vaccines, we conducted parental interviews and chart review.

RESULTS

Median (interquartile range) age was 7.6 years for cases and 9.3 for controls (p = 0.44). Infection in the week prior to stroke, or interview date for controls, was reported in 18% of cases, vs 3% of controls, conferring a 6.3-fold increased risk of AIS (p < 0.0001); upper respiratory infections were most common. Prevalence of preceding infection was similar across stroke subtypes: arteriopathic, cardioembolic, and idiopathic. Use of vasoactive cold medications was similarly low in both groups. Children with some/few/no routine vaccinations were at higher stroke risk than those receiving all or most (odds ratio [OR] 7.3, p = 0.0002). In an age-adjusted multivariate logistic regression model, independent risk factors for AIS included infection in the prior week (OR 6.3, p < 0.0001), undervaccination (OR 8.2, p = 0.0004), black race (compared to white; OR 1.9, p = 0.009), and rural residence (compared to urban; OR 3.0, p = 0.0003).

CONCLUSIONS

Infection may act as a trigger for childhood AIS, while routine vaccinations appear protective. Hence, efforts to reduce the spread of common infections might help prevent stroke in children.

Persistent blood stream infection in patients supported with a continuous-flow left ventricular assist device is associated with an increased risk of cerebrovascular accidents

BACKGROUND

Common adverse events in patients supported with Continuous-flow left ventricular assist devices (CF-LVAD) include infections and cerebrovascular accidents (CVA). Some studies have suggested a possible association between blood stream infection (BSI) and CVA.

METHODS AND RESULTS

Medical records of patients who received Heartmate II (HMII) CF-LVADs in 2008-2012 at a single center were reviewed. CVA was categorized as either hemorrhagic (HCVA) or ischemic (ICVA). BSI was divided into persistent (pBSI) and nonpersistent (non-pBSI). pBSI was defined as BSI with the same organism on repeated blood culture >72 hours from initial blood culture despite antibiotics. Univariate and multivariate analyses were performed to determine predictors. A total of 149 patients had HMII implanted; 76% were male, and the overall mean age was 55.4 ± 13 years. There were a total of 19 (13%) patients who had CVA (7 HCVA and 12 ICVA) at a median of 295 days (range 5-1,096 days) after implantation. There were a total of 28 (19%) patients with pBSI and 17 (11%) patients with non-pBSI. Patients with pBSI had a trend toward greater BMI (31 kg/m(2) vs 27 kg/m(2); P = .09), and longer duration of support (1,019 d vs 371 d; P < .001) compared with those with non-pBSI. Persistent BSI was associated with an increased risk of mortality and with all-cause CVA on multivariate analysis (odds ratio [OR] 5.97; P = .003) as well as persistent Pseudomonas aeruginosa infection (OR 4.54; P = .048).

CONCLUSIONS

Persistent BSI is not uncommon in patients supported by CF-LVAD and is highly associated with all-cause CVA and increased all-cause mortality.

Systemic infection and inflammation as trigger factors of ischemic stroke

Background

Chronic risk factors are well understood in cases of stroke as well as myocardial infarction. Till date, several triggers for stroke are still under evaluation. Researchers have previously evaluated the relationship between preceding infection and inflammation and stroke onset.

Purpose

The purpose of study is to define the stroke triggers in a better way and to provide little more information for early intervention by controlling infections or other trigger factors

Methods

In this retrospective study, a standardized questionnaire was carried out to evaluate the signs, symptoms of preceding (<14 days) infection, physical/mental health, drug history, TIA etc. of 70 ischemic stroke patients and 80 non-stroke out-patient department patients as control groups. Important biochemical tests e.g. high sensitivity CRP, leukocytes count, blood sugar, lipid profile, etc. were also taken into consideration. Recent (15 days) prior infection, mainly respiratory tract infection and urinary tract infection, which were likely to be important stroke triggers, were compared between the ischemic stroke groups and the non-stroke patients (control group).

Results

It was found that respiratory tract infection is the most common type of infection (48.5%) compared with the non-stroke control group (30%). Apart from this, there were clinical evidence of infections like gastroenteritis, RTI, UTI etc which were biochemically established by leukocytosis and increased high-sensitivity C-Reactive Protein levels, well-known early diagnostic tools that have good predictive value. This study reveals that well-controlled diabetic, hypertensive or non-diabetic normotensive patients can suddenly develop ischemic stroke following recent infection as evidenced by clinical features, increased levels of high-sensitivity CRP and leukocytosis.

Conclusion

These diagnostic tools implicate the value of early treatment of febrile illness and introduction or adjustment of doses of antiplatelet agents, antibiotics, etc. to reduce the actual stroke incidence, though it needs multicentre large community based prospective trials to evaluate stroke prone state and effective preventive measures tools at the same time.

Timing and number of minor infections as risk factors for childhood arterial ischemic stroke

OBJECTIVE

In a population-based case-control study, we examined whether the timing and number of minor infections increased risk of childhood arterial ischemic stroke (AIS).

METHODS

Among 102 children with AIS and 306 age-matched controls identified from a cohort of 2.5 million children in a large integrated health care plan (1993-2007), we abstracted data on all medical visits for minor infection within the 2 years prior to AIS or index date for pairwise age-matched controls. We excluded cases of AIS with severe infection (e.g., sepsis, meningitis). Using conditional logistic regression, we examined the effect of timing and total number of minor infections on stroke risk.

RESULTS

After adjusting for known pediatric stroke risk factors, the strongest association between infection and AIS was observed for infectious visits ≤3 days prior to stroke (odds ratio [OR] 12.1, 95% confidence interval [CI] 2.5, 57, p = 0.002). Respiratory infections represented 80% of case infections in that time period. Cases had more infectious visits, but not significantly so, for all time periods ≥4 days prior to the stroke. A greater cumulative number of infectious visits over 2 years did not increase risk of AIS.

CONCLUSIONS

Minor infections appear to have a strong but short-lived effect on pediatric stroke risk, while cumulative burden of infection had no effect. Proposed mechanisms for the link between minor infection and stroke in adults include an inflammatory-mediated prothrombotic state and chronic endothelial injury. The transient effect of infection in children may suggest a greater role for a prothrombotic mechanism.

Acute infection contributes to racial disparities in stroke mortality

OBJECTIVE

It is unknown whether racial differences in exposure to acute precipitants of stroke, specifically infection, contribute to racial disparities in stroke mortality.

METHODS

Among participants in the nationally representative Health and Retirement Study with linked Medicare data (1991-2007), we conducted a case-crossover study employing within-person comparisons to study racial/ethnic differences in the risks of death and hospitalization from ischemic stroke following acute infection.

RESULTS

There were 964 adults hospitalized for ischemic stroke. Acute infection increased the 30-day risks of ischemic stroke death (5.82-fold) and ischemic stroke hospitalization (1.87-fold). Acute infection was a more potent trigger of acute ischemic stroke death in non-Hispanic blacks (odds ratio [OR] 39.21; 95% confidence interval [CI] 9.26-166.00) than in non-Hispanic whites (OR 4.50; 95% CI 3.14-6.44) or Hispanics (OR 5.18; 95% CI 1.34-19.95) (race-by-stroke interaction, p = 0.005). When adjusted for atrial fibrillation, infection remained more strongly associated with stroke mortality in blacks (OR 34.85) than in whites (OR 3.58) and Hispanics (OR 3.53). Acute infection increased the short-term risk of incident stroke similarly across racial/ethnic groups. Infection occurred often before stroke death in non-Hispanic blacks, with 70% experiencing an infection in the 30 days before stroke death compared to a background frequency of 15%.

CONCLUSIONS

Acute infection disproportionately increases the risk of stroke death for non-Hispanic blacks, independently of atrial fibrillation. Stroke incidence did not explain this finding. Acute infection appears to be one factor that contributes to the black-white disparity in stroke mortality.

Investigating the association between influenza vaccination and reduced stroke risk

Acute infections, mainly of the respiratory tract, have consistently been demonstrated to considerably increase the risk of stroke. At present, prospective interventional trials are lacking and there is no proof of the effectiveness of any therapeutic anti-infective strategy in stroke prevention. However, some new evidence from observational studies lends support to the idea that influenza vaccination may contribute importantly to fighting stroke. Although final proof of efficacy is still missing, patients with previous cerebral ischemia and subjects of any age at high risk of stroke should be encouraged to receive annual influenza vaccination.

Incidence of first ever stroke during Hajj ceremony

BACKGROUND

The Hajj Ceremony, the largest annual gathering in the world, is the most important life event for any Muslim. This study was designed to evaluate the incidence of stroke among Iranian pilgrims during the Hajj ceremony.

METHODS

We ascertained all cases of stroke occurring in a population of 92,974 Iranian pilgrims between November 27, 2007 and January 12, 2008. Incidence and risk factors of the first ever stroke in Hajj pilgrims were compared, within the same time frame, to those of the Mashhad residents, the second largest city in Iran. Data for the latter group were extracted from the Mashhad Stroke Incidence Study (MSIS) database.

RESULTS

During the study period, 17 first-ever strokes occurred in the Hajj pilgrims and 40 first-ever stroke strokes occurred in the MSIS group. Overall, the adjusted incidence rate of first ever stroke in the Hajj cohort was lower than that of the MSIS population (9 vs. 16 per 100,000). For age- and gender-specific subgroups, the Hajj stroke crude rates were in general similar to or lower than the general population of Mashhad, Iran, with the exception of women aged 35 to 44 years and aged >75 years who were at greater risk of having first-ever stroke than the non-pilgrims of the same age.

CONCLUSION

The first ever stroke rate among Iranian Hajj pilgrims was lower than that of the general population in Mashhad, Iran, except for females 35-44 or more than 75 years old. The number of events occurring during the Hajj suggests that Islamic countries should consider designing preventive and screening programs for pilgrims.

The immune system in stroke: clinical challenges and their translation to experimental research

Stroke represents an unresolved challenge for both developed and developing countries and has a huge socio-economic impact. Although considerable effort has been made to limit stroke incidence and improve outcome, strategies aimed at protecting injured neurons in the brain have all failed. This failure is likely to be due to both the incompleteness of modelling the disease and its causes in experimental research, and also the lack of understanding of how systemic mechanisms lead to an acute cerebrovascular event or contribute to outcome. Inflammation has been implicated in all forms of brain injury and it is now clear that immune mechanisms profoundly influence (and are responsible for the development of) risk and causation of stroke, and the outcome following the onset of cerebral ischemia. Until very recently, systemic inflammatory mechanisms, with respect to common comorbidities in stroke, have largely been ignored in experimental studies. The main aim is therefore to understand interactions between the immune system and brain injury in order to develop novel therapeutic approaches. Recent data from clinical and experimental research clearly show that systemic inflammatory diseases -such as atherosclerosis, obesity, diabetes or infection - similar to stress and advanced age, are associated with dysregulated immune responses which can profoundly contribute to cerebrovascular inflammation and injury in the central nervous system. In this review, we summarize recent advances in the field of inflammation and stroke, focusing on the challenges of translation between pre-clinical and clinical studies, and potential anti-inflammatory/immunomodulatory therapeutic approaches.

The role of the cerebral capillaries in acute ischemic stroke: the extended penumbra model

The pathophysiology of cerebral ischemia is traditionally understood in relation to reductions in cerebral blood flow (CBF). However, a recent reanalysis of the flow-diffusion equation shows that increased capillary transit time heterogeneity (CTTH) can reduce the oxygen extraction efficacy in brain tissue for a given CBF. Changes in capillary morphology are typical of conditions predisposing to stroke and of experimental ischemia. Changes in capillary flow patterns have been observed by direct microscopy in animal models of ischemia and by indirect methods in humans stroke, but their metabolic significance remain unclear. We modeled the effects of progressive increases in CTTH on the way in which brain tissue can secure sufficient oxygen to meet its metabolic needs. Our analysis predicts that as CTTH increases, CBF responses to functional activation and to vasodilators must be suppressed to maintain sufficient tissue oxygenation. Reductions in CBF, increases in CTTH, and combinations thereof can seemingly trigger a critical lack of oxygen in brain tissue, and the restoration of capillary perfusion patterns therefore appears to be crucial for the restoration of the tissue oxygenation after ischemic episodes. In this review, we discuss the possible implications of these findings for the prevention, diagnosis, and treatment of acute stroke.

[Central nervous system embolism in the course of infective endocarditis]

Despite the progress made in diagnosis and treatment of heart valve diseases, the incidence of infective endocarditis (IE) remains constant. It is still associated with high mortality and high rate of embolic complications, including most dangerous one, i.e. stroke. It has a significant impact on further treatment and qualifications for cardiac surgery. In this paper, the authors discuss the epidemiology, mechanisms of stroke and its impact on the qualifications for cardiac surgery. The authors discuss the problem of clinically silent central nervous system embolism in the course of IE and the usefulness of neuroimaging and markers of central nervous system damage in diagnosis of cerebral embolism.

The effects of ceftriaxone on skill learning and motor functional outcome after ischemic cortical damage in rats

PURPOSE

Ceftriaxone, a β-lactam antibiotic, can selectively enhance the expression of glutamate transporter 1 (GLT1), the most abundant astrocytic glutamate transporter expressed in the cortex. It has been found to have neuroprotective effects when administered prior to brain ischemic damage or during the acute phase post-stroke, but its effects in chronic period have not been examined.

METHODS

We examined the effects of ceftriaxone on the acquisition of motor skill and the functional outcome after focal ischemic cortical lesions. In adult male rats, ceftriaxone (200 mg/kg) or vehicle was intraperitoneally injected daily for 5 days, a treatment regime previously established to upregulate GLT-1. This preceded 28 days of skilled reach training in intact animals or began 3 days following lesions, followed by 5 weeks of rehabilitative reach training.

RESULTS

In intact rats, ceftriaxone did not affect skill learning rate or final performance. Following ischemic lesions, though there was no significant difference in lesion sizes between groups, ceftriaxone exacerbated initial deficits in reaching performance.

CONCLUSION

These findings of detrimental effects on motor functional outcome suggest that ceftriaxone may be more useful for neuroprotection during the acute phase of ischemia than for functional recovery in the post-acute period after ischemic damage.

Polymorphism of tumor necrosis factor alpha (TNF-alpha) gene promoter, circulating TNF-alpha level, and cardiovascular risk factor for ischemic stroke

Background

Tumor necrosis factor-α (TNF-α) is one of the most typical pro-inflammatory cytokines with both beneficial and destructive properties for the central nervous system. Increasing evidences have demonstrated the important role of TNF-α in the development of ischemic stroke, but studies examining the possible association with stroke or direct functional effects of polymorphisms in TNF-α have been contradictory.

Findings

In this study, a 2-kb length of the proximal promoter of the TNF-α was screened and four polymorphisms were investigated in the case–control study. Our data confirmed the association between -308G/A variant with stroke in 1,388 stroke patients and 1,027 controls and replicated in an independent population of 961 stroke patients and 821 controls (odds ratio (OR) = 1.34, 95% confidence interval (CI) =1.02 to 1.77 and OR = 1.56, 95% CI = 1.09 to 2.23, respectively). To reconcile the association between polymorphisms and stroke and to give a comprehensive picture of the genetic architecture of this important gene, we performed a meta-analysis of 15 published studies in an Asian population. Our results demonstrated an association between rs1800629 and ischemic stroke (OR = 1.43, 95% CI = 1.21 to 1.69). Another meta-analysis results of 14 studies demonstrated that ischemic stroke patients have higher serum TNF-α level than the control subjects (standardized mean difference (SMD) = 2.33, 95% CI = 1.85 to 2.81). In vitro evaluation of potential interaction between variants of the TNF-α gene (−308G/A, -857C/T, and -1031T/C) demonstrated that these three polymorphisms could interact together to determine the overall activity of the TNF-α gene.

Conclusions

These findings strongly implicate the involvement of TNF-α in the pathogenesis of stroke.

Systemic immune activation shapes stroke outcome

Stroke is a major cause of morbidity and mortality, and activation of the immune system can impact on stroke outcome. Although the majority of research has focused on the role of the immune system after stroke there is increasing evidence to suggest that inflammation and immune activation prior to brain injury can influence stroke risk and outcome. With the high prevalence of co-morbidities in the Western world such as obesity, hypertension and diabetes, pre-existing chronic 'low-grade' systemic inflammation has become a customary characteristic of stroke pathophysiology that needs to be considered in the search for new therapies. The importance of the immune system in stroke has been demonstrated in a number of ways, both experimentally and in the clinical setting. This review will focus on the effect of immune activation arising from systemic inflammatory conditions and infection, how it affects the incidence and outcomes of stroke, and the possible underlying mechanisms involved. This article is part of a Special Issue entitled 'Neuroinflammation in neurodegeneration and neurodysfunction'.

Falling temperature and colder weather are associated with an increased risk of aneurysmal subarachnoid hemorrhage

OBJECTIVE

To use weather data to predict increased incidence of aneurysmal subarachnoid hemorrhage (aSAH) at a large institution with an extensive referral network in response to falling temperatures.

METHODS

In a retrospective study, 1175 prospectively collected aSAH cases accrued over 18 years from one hospital were reviewed to determine if season, maximum ambient temperature (MAT), average relative humidity, and atmospheric pressure were related to incidence of aSAH at that institution on a given day. A Poisson regression model was used to assess daily risk of incident aSAH based on daily MAT and 1-day change in MAT.

RESULTS

A MAT decrease of 1°F from one day to the next was associated with a 0.6% increase in risk of aSAH (relative risk [RR]=1.006, P=0.016). The increased risk associated with MAT decrease from the previous day was especially strong for female patients (RR=1.008/°F, P=0.007) and drove the overall model, representing 72% of cases. In addition, warmer temperatures were associated with a decreased risk of aSAH; each 1°F increase in temperature compared with the previous day was associated with a 0.3% decrease in risk of aSAH (RR=0.997; P<0.001).

CONCLUSIONS

A 1-day decrease in temperature and colder daily temperatures were associated with an increased risk of incident aSAH at a single institution with a large referral network. These variables appeared to act synergistically and independently of season. These relationships were particularly predominant in the fall when the transition from warmer to colder temperatures occurred.

Stressful Life Events as Triggers of Ischemic Stroke: A Case-Crossover Study

Background

Acute stressors, such as stressful life events, might trigger ischemic stroke.

Aims

Our objective was to investigate the association between life events exposure and ischemic stroke onset.

Methods

Consecutive patients were interviewed about life events exposure (e.g. bereavement) using the Interview for Recent Life Events. Using a case-crossover approach, life events exposure within one month of stroke onset (hazard period) was compared with exposure during five control periods of one month preceding the hazard period. Similarly, life events exposure within one week of stroke onset was compared with exposure during three control periods of one week. Odds ratios and 95% confidence intervals were calculated using conditional logistic regression.

Results

Two hundred forty-seven patients were interviewed within a median time of five days (interquartile range 3–7). Life events belonging to bereavement, health, and other categories accounted for half of life events. Over the six-month period, 187 patients were exposed to ≥1 life events. Patients were exposed to ≥1 life events more often during the first month preceding stroke onset than during the five control periods (odds ratio = 2·96; 95% confidence interval, 2·19–4·00). Over the four-week period, 97 patients were exposed to ≥1 life events. Patients were exposed to ≥1 life events more often during the first week preceding stroke onset than during the three control periods (odds ratio = 2·10; 1·40–3·17).

Conclusions

Recent life events exposure is associated with an increased risk of ischemic stroke.

Common infections and the risk of stroke

The occurrence of stroke in populations is incompletely explained by traditional vascular risk factors. Data from several case-control studies and one large study using case series methodology indicate that recent infection is a temporarily acting, independent trigger factor for ischemic stroke. Both bacterial and viral infections, particularly respiratory tract infections, contribute to this association. A causal role for infection in stroke is supported by a graded temporal relationship between these conditions, and by multiple pathophysiological pathways linking infection and inflammation, thrombosis, and stroke. Furthermore, observational studies suggest that influenza vaccination confers a preventive effect against stroke. Case-control and prospective studies indicate that chronic infections, such as periodontitis, chronic bronchitis and infection with Helicobacter pylori, Chlamydia pneumoniae or Cytomegalovirus, might increase stroke risk, although considerable variation exists in the results of these studies, and methodological issues regarding serological results remain unresolved. Increasing evidence indicates that the aggregate burden of chronic and/or past infections rather than any one single infectious disease is associated with the risk of stroke. Furthermore, genetic predispositions relating to infection susceptibility and the strength of the inflammatory response seem to co-determine this risk. Here, we summarize and analyze the evidence for common acute and chronic infectious diseases as stroke risk factors.

"I feel like half my body is clogged up": Lay models of stroke in Central Aceh, Indonesia

Stroke in low and middle income countries is an increasing cause of death and disability, with rates and the estimated burden considerably higher than that of high income countries. Lay explanatory models are believed to be one of the major influences on health seeking behaviour and essential to understand for appropriate education strategies. Despite stroke being a considerable health concern in Indonesia and particularly in Aceh, no studies to date have explored lay stroke models in that context. This paper presents the findings of a qualitative study informed by both hermeneutic phenomenology and ethnography. Based in rural communities in Bener Meriah and Aceh Tengah in Central Aceh, Indonesia, data were gathered through interviews, photographs and observations with 11 persons with stroke (aged 32-69 years) and 18 of their carers. Fieldwork was conducted over nine months between 2007 and 2008. The study examined lay concepts of stroke, described as a condition resulting from a local blockage in blood from multiple causes, many of which are not recognised within the biomedical frame. The blockage is understood to be reversible and therefore the condition curable. This understanding is embedded and sustained in the specific political, cultural, religious and social context. The results illustrate similarities and differences with other cross-cultural studies and suggest areas of future research and points of consideration for stroke education strategies.

Pathways to further boost treatment rates and clinical outcomes in hospitalized stroke patients

Inpatient quality improvement initiatives have been associated with impressive improvements in evidence-based discharge treatment rates in hospitalized stroke patients. However, these programs have generally focused only on optimizing recurrent stroke prevention strategies among ischemic stroke patients. Many patients hospitalized with recent symptomatic cerebral ischemia are also at risk for future ischemic episodes emanating from other vascular beds, and the inpatient setting could represent an opportunity to screen and appropriately manage such patients who harbor cross-vascular risk. The stroke hospitalization may also be ideal for identifying stroke patients susceptible to a highly preventable yet common trigger of vascular events and poor clinical outcomes like influenza infection. Finally, several hospital-based prevention measures are underutilized in patients hospitalized with intracerebral hemorrhage (ICH) compared with those with ischemic stroke or transient ischemic attack, and so protocols geared at enhancing prevention of ICH recurrence, are certainly warranted. This article presents pathways (algorithms, pocket cards, preprinted orders) developed from expert consensus prevention guidelines and implemented within a broader stroke inpatient quality improvement program, which target patients highly vulnerable to future coronary events, poor clinical outcomes following influenza infection, and recurrent ICH.

The role of functional polymorphisms of the TNF-alpha gene promoter in the risk of ischemic stroke in Chinese Han and Uyghur populations: Two case-control studies

BACKGROUND

Increasing evidences for the role of tumor necrosis factor-alpha (TNF-alpha) in the occurrence of ischemic stroke (IS) have shown that it belongs to pro-inflammatory cytokines and carries functional polymorphisms (TNF-alpha -238G/A and TNF-alpha -308G/A) in its promoter region, which affect their transcription rate and plasma cytokine level. We determined the association between these polymorphisms and the occurrence of IS in the Chinese Han and Uyghur populations.

METHODS

The TNF-alpha -238G/A and TNF-alpha -308G/A polymorphisms were determined by TaqMan SNP Genotyping assays in cases (n=748) and controls (n=748). Multivariate logistic regression analysis was used to show the association between the TNF-alpha genotypes and the IS events.

RESULTS

No significant difference was found in the association between TNF-alpha -238G/A and IS in both ethnic populations. The result showed that carriage of the TNF-alpha -308GA was a decreased risk of IS in both Han and Uyghur populations (OR:0.453, 0.213). In addition, the significant difference in GA frequency in TNF-alpha was found between the two ethnic controls (P=0.000).

CONCLUSIONS

TNF-alpha -308 GA heterozygous may be an independent protective factor for IS in the Chinese Han and Uyghur populations.

Self-perceived psychological stress and ischemic stroke: a case-control study

BACKGROUND

A growing body of evidence suggests that psychological stress contributes to coronary artery disease. However, associations between stress and stroke are less clear. In this study, we investigated the possible association between ischemic stroke and self-perceived psychological stress, as measured by a single-item questionnaire, previously reported to be associated with myocardial infarction.

METHODS

In the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), 600 consecutive patients with acute ischemic stroke (aged 18 to 69 years) and 600 age-matched and sex-matched population controls were recruited. Ischemic stroke subtype was determined according to Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. Self-perceived psychological stress preceding stroke was assessed retrospectively using a single-item questionnaire.

RESULTS

Permanent self-perceived psychological stress during the last year or longer was independently associated with overall ischemic stroke (multivariate adjusted odds ratio (OR) 3.49, 95% confidence interval (CI) 2.06 to 5.93). Analyses by stroke subtype showed that this association was present for large vessel disease (OR 3.91, 95% CI 1.58 to 9.67), small vessel disease (OR 3.20, 95% CI 1.64 to 6.24), and cryptogenic stroke (OR 4.03, 95% CI 2.34 to 6.95), but not for cardioembolic stroke (OR 1.48, 95% CI 0.64 to 3.39).

CONCLUSION

In this case-control study, we found an independent association between self-perceived psychological stress and ischemic stroke. A novel finding was that this association differed by ischemic stroke subtype. Our results emphasize the need for further prospective studies addressing the potential role for psychological stress as a risk factor for ischemic stroke. In such studies ischemic stroke subtypes should be taken into consideration.

Differentiating ischemic stroke subtypes: risk factors and secondary prevention

Ischemic strokes account for 87% of all strokes in the US. Patients who suffer an initial ischemic stroke or transient ischemic attack are at risk for recurrent strokes, as well as ischemic events in the coronary and peripheral vasculatures. Lifestyle modifications and pharmacological and surgical interventions are effective in reducing the risk of recurrent events in all stroke patients, and evidence-based guidelines for secondary stroke prevention are available. However, increasing evidence indicates that risk factors may be differentially associated with specific ischemic stroke subtypes. In the future, exploiting these differential associations may facilitate secondary stroke prevention and, therefore, improve patient outcomes.

Vaccines in development to prevent and treat atherosclerotic disease

Coronary heart disease (CHD) remains the leading cause of death in the United States. Immune mechanisms have been recently proposed to play an important role in the development of atherosclerotic plaques in CHD. Heat shock proteins and oxidized low-density lipoprotein are proinflammatory substances that have been shown to have an important role in the pathogenesis of atherosclerosis, and are now targets for clinical vaccine development. In addition, a vaccine has been developed to inhibit cholesteryl ester transfer protein. It is now recognized that many medications used to combat plaque development and rupture have significant anti-inflammatory effects and these effects are critical for drug efficacy. The influenza vaccine is associated with an atheroprotective effect. In addition, a nicotine vaccine, an antiangiotensin vaccine, and an anti-obesity vaccine may play a therapeutic role in modifying known risk factors for the development of atherosclerosis and its complications. This article reviews these vaccines as possible additions to the armamentarium of atheroprotective treatment modalities.

Systemic infection, inflammation and acute ischemic stroke

Extensive evidence implicates inflammation in multiple phases of stroke etiology and pathology. In particular, there is growing awareness that inflammatory events outside the brain have an important impact on stroke susceptibility and outcome. Numerous conditions, including infection and chronic non-infectious diseases, that are established risk factors for stroke are associated with an elevated systemic inflammatory profile. Recent clinical and pre-clinical studies support the concept that the systemic inflammatory status prior to and at the time of stroke is a key determinant of acute outcome and long-term prognosis. Here, we provide an overview of the impact of systemic inflammation on stroke susceptibility and outcome. We discuss potential mechanisms underlying the impact on ischemic brain injury and highlight the implications for stroke prevention, therapy and modeling.

Gene expression in peripheral blood differs after cardioembolic compared with large-vessel atherosclerotic stroke: biomarkers for the etiology of ischemic stroke

There are no biomarkers that differentiate cardioembolic from large-vessel atherosclerotic stroke, although the treatments differ for each and approximately 30% of strokes and transient ischemic attacks have undetermined etiologies using current clinical criteria. We aimed to define gene expression profiles in blood that differentiate cardioembolic from large-vessel atherosclerotic stroke. Peripheral blood samples were obtained from healthy controls and acute ischemic stroke patients (<3, 5, and 24 h). RNA was purified, labeled, and applied to Affymetrix Human U133 Plus 2.0 Arrays. Expression profiles in the blood of cardioembolic stroke patients are distinctive from those of large-vessel atherosclerotic stroke patients. Seventy-seven genes differ at least 1.5-fold between them, and a minimum number of 23 genes differentiate the two types of stroke with at least 95.2% specificity and 95.2% sensitivity for each. Genes regulated in large-vessel atherosclerotic stroke are expressed in platelets and monocytes and modulate hemostasis. Genes regulated in cardioembolic stroke are expressed in neutrophils and modulate immune responses to infectious stimuli. This new method can be used to predict whether a stroke of unknown etiology was because of cardioembolism or large-vessel atherosclerosis that would lead to different therapy. These results have wide ranging implications for similar disorders.

Acute ischaemic stroke and infection: recent and emerging concepts

The relation between acute ischaemic stroke and infection is complex. Infection appears to be an important trigger that precedes up to a third of ischaemic strokes and can bring about stroke through a range of potential mechanisms. Infections that present subsequent to stroke also complicate up to a third of cases of stroke and might worsen outcome. Inflammatory responses, which are a defence mechanism against infection but can also be a pathogenic mechanism that precipitates stroke and neurological sequelae, are important features. Although factors such as stroke severity and dysphagia are important predictors of poststroke infection, there is evidence from experimental and clinical settings of impaired immunity or brain-induced immunodepression after stroke. Greater understanding of the relation between inflammation and both infection and ischaemic mechanisms is needed. This might be particularly important because new treatment strategies for acute ischaemic stroke are being investigated, including those that modulate cytokines and the immune system.

Exposure to the US Stroke Buckle as a risk factor for cerebrovascular mortality

BACKGROUND

For decades, the Stroke Buckle region in the southeastern USA has had a high incidence of deaths from cerebrovascular disease relative to the rest of the country. We test here the possibility that temporary exposure to the Stroke Buckle can explain some of the excessive stroke mortality there.

METHODS

We examined all US death records between 1979 and 1988, noting whether individuals died inside or outside the 153-county Stroke Buckle in the coastal plains of North Carolina, South Carolina and Georgia. We also noted the decedents' county of residence, which was coded separately. Proportionate mortality ratios (PMRs) were used to assess the risk of dying of a stroke.

RESULTS

Stroke Buckle residents who died in their home county were at an increased risk of dying of a stroke (PMR = 130.2; 95% confidence interval, CI = 128.9-131.6; p < 0.0001). Visitors to the Buckle were also at an increased risk of dying of a stroke (PMR = 111.9; 95% CI = 107.5-116.2; p < 0.0001), and Buckle residents who died while outside of the region were less likely to die of a stroke (PMR = 89.9; 95% CI = 86.2-93.6; p < 0.0001).

CONCLUSIONS

These results show that even short-term exposure to the Stroke Buckle accounts for some of the elevation in stroke deaths there.

2006 Curt P. Richter award winner: Social influences on stress responses and health

Both positive and negative social interactions can modulate the hypothalamic-pituitary-adrenal (HPA) axis and influence recovery from injuries and illnesses, such as wounds, stroke, and cardiac arrest. Stress exacerbates neuronal death following stroke and cardiac arrest, and delays cutaneous wound healing, via a common mechanism involving stress-induced increases in corticosterone, acting on glucocorticoid receptors. In contrast, hamsters and mice that form social bonds are buffered against stress and heal cutaneous wounds more quickly than socially isolated animals, presumably because the physical contact experienced by the pairs releases oxytocin, which in turn suppresses the HPA axis and facilitates wound healing. Social housing also decreases stroke-induced neuronal death and improves functional recovery, but the mechanism appears to involve suppressing the inflammatory response that accompanies stroke, rather than alterations in HPA axis activity. An interaction between the HPA axis and immune system determines stroke outcome in neonatally manipulated mice that exhibit life-long dampening of the HPA axis. Taken together, these studies provide support for the detrimental effects of stress and identify potential mechanisms underlying the well-documented clinical observation that social support positively influences human health.

Development of cerebral infarction shortly after intracerebral hemorrhage

BACKGROUND AND PURPOSE

Cerebral infarction (CI) occurring soon after intracerebral hemorrhage (ICH) has been rarely reported. The purpose of the present study was to characterize this condition and discuss the possible pathophysiology.

METHOD

We retrospectively studied 6 patients who developed CI within 10 days after the onset of ICH.

RESULTS

The initial ICHs were located in the putamen (n=3), thalamus (n=2) and cerebellum (n=1), and were considered to be caused by hypertension in all of the patients. They showed sudden worsening (n=4) or change in neurologic symptoms (n=2) within 10 days after the initial ICH. Follow-up imaging revealed corresponding lacunar (n=2) and territorial (n=4) infarcts. Possible factors related to the development of new CIs included mechanical compression of cerebral vessels (n=2), dehydration (n=4), hypotension (n=2), infection (n=2) and concomitant small-vessel pathology (n=2).

CONCLUSIONS

ICH may predispose certain patients to the development of infarcts through a combination of mechanisms, including mechanical compression of cerebral vessels, hemodynamic instability, inflammation and concomitant small-vessel pathology.

Influenza- and RSV-associated hospitalizations among adults

We estimated influenza- and respiratory syncytial virus (RSV)-associated hospitalizations by age, high-risk status and outcome, during the 1996/1997-1999/2000 respiratory seasons among adults who did not receive influenza vaccine. Using three health maintenance organization (HMO) databases and local viral surveillance data, we identified weeks when influenza and RSV were circulating and estimated influenza- and RSV-associated hospitalizations. Persons aged > or = 65 years with and without high-risk conditions had significantly increased rates of influenza-associated hospitalizations for pneumonia and influenza, and circulatory and respiratory diseases. Persons aged > or = 65 years with high-risk conditions also had significantly increased rates of influenza-associated hospitalizations for cardiac conditions (16.9 per 10,000 person periods). Relative to the influenza estimates for high-risk persons > or = 65 years, we found lower rates of RSV-associated hospitalizations for pneumonia and influenza diseases (23.4 per 10,000 person periods), cardiac diseases (4.3 per 10,000 person periods) and circulatory and respiratory diseases (44.0 per 10,000 person periods). Among low-risk persons aged 50-64 years, we did not identify significantly elevated rates of influenza- or RSV-associated hospitalizations. Excess hospitalization estimates among adults aged > or = 65 years and high-risk 50-64 year olds during the influenza season suggest that these groups should have priority for influenza vaccine during vaccine shortages.

Infection as a risk factor for stroke

Persisting disability requiring professional healthcare or help in daily life activities can be expected in a third to a half of all stroke survivors. It is mainly the elderly that are affected. For the increasingly aging population of Western societies, stroke represents an increasing social and economic burden. Besides the existing therapeutic options, additional treatment and prevention strategies are needed. Traditional risk factors do not explain all clinical and epidemiological features of stroke. Recently, the association between infectious and inflammatory processes and the occurrence of vascular disease has been established. This review summarizes the current evidence of infections as stroke risk factors and of potential anti-infective strategies as future methods of stroke prevention.

Rat neonatal immune challenge alters adult responses to cerebral ischaemia

Infection, inflammation, and hyperthermia associated with cerebral ischaemia are known to contribute to enhanced neuronal cell loss and more severe behavioural deficits. Because neonatal exposure to an immune challenge has been shown to alter the severity of inflammatory and febrile responses to a further immune challenge experienced in adulthood, we hypothesised that this could also alter temperature responses and neuronal survival after ischaemia. Thus, male Sprague-Dawley rats were treated at postnatal day 14 with a single injection of the bacterial endotoxin lipopolysaccharide (LPS) and were examined as adults for temperature changes, behavioural deficits, and neuronal cell loss associated with global cerebral ischaemia after a two-vessel occlusion (2VO). Neonatally LPS-treated rats showed behavioural differences in a novel object exploration paradigm, as well as altered temperature responses to the 2VO compared with neonatally saline-treated controls. Interestingly, these neonatally LPS-treated rats also showed increased cell loss in the central nucleus of the amygdala, a region that is important in the processing of emotional responses, but that is not usually examined in animal models of cerebral ischaemia. No differences were seen in the CA1, CA3, or dentate gyrus regions of the hippocampus. This work shows the importance of examining brain regions other than the hippocampus in association with global ischaemia. We also highlight the importance of the early period of development in programming an animal's ability to deal with injury such as cerebral ischaemia in adulthood.

Streptococcus oralis as a risk factor for middle cerebral artery thrombosis

We reported a case of an 8-year-old boy who was presented to the emergency department with left-sided hemiparesis. Computed tomography showed hypodense areas in the territory of the right middle cerebral artery, indicating acute cerebral infarct. Diagnostic evaluation was performed to identify the etiology. On the eighteenth day of hospitalization, cerebrospinal fluid cultures yielded Streptococcus oralis. We hypothesized that the source of the oral pathogen was an abscess belonging to his upper left fourth tooth, which, by a transient bacteremia, had invaded the central nervous system, and skipping the meninges caused local inflammatory arteritis of the carotid artery, leading to cerebral infarction. Sulbactam-ampicillin therapy was initiated for 14 days, and he was discharged with anticoagulation therapy.

Assessment of relations between clinical outcome of ischemic stroke and activity of inflammatory processes in the acute phase based on examination of selected parameters

BACKGROUND AND PURPOSES

Inflammatory factors play an important role in the pathogenesis of ischemic stroke. They may influence circulation during the acute phase of stroke and enhance the ischemic region.

MATERIALS AND METHODS

We examined 51 patients--36 patients in the early stage of stroke, i.e. the first 24 h after onset. Of these, 15 patients had infection and 21 had no infection during the week preceding stroke. There were 15 patients with noninflammatory diseases in the control group. We analyzed parameters of inflammation such as: activity of serum chitotriosidase by fluorimetric assay, C-reactive proteins (CRP), number of white body cells (WBCs), IgG and fibrinogen. We also assessed the neurological stage according to the Scandinavian Stroke Scale (SSS).

RESULTS

In our study, we observed a statistically significant difference (p < 0.05) in the activity of most parameters of inflammation. This difference could be seen in the levels of CRP, number of WBCs and the activity of chitotriosidase, apart from IgG and fibrinogen, between the control group and groups with versus without infection. A significantly increased level of CRP (p < 0.0005) and fibrinogen (p > 0.01) was found on the first day in the stroke group as compared to the control group. The neurological stage on day 4 after stroke, assessed according to the SSS, was significantly worse in the group of patients with infection before stroke than in stroke patients without infection (p < 0.008).

CONCLUSION

These results suggest the importance of active inflammatory processes in the pathogenesis of stroke. We observed increased activity of chitotioridase, a parameter of the inflammatory process, in stroke. This study is one more proof that inflammatory processes caused by infection may influence the occurrence of stroke and worsen its outcome. It could be another step towards understanding immunological processes during the acute phase of stroke. The study may also help establish new diagnostic and therapeutic strategies and could be a useful tool for prophylaxis.

Embolic events in infective endocarditis: a review and report of 4 cases

Infective endocarditis (IE) remains a dangerous disease in terms of morbidity and mortality. Valve damage with or without congestive heart failure, paravalvular extension, embolization of vegetation, damage due to immunological involvement and septic shock are the main complications of IE. Embolic events are frequent and life-threatening complications of IE. In previous series, the reported figures of embolic complication vary from 10 to 50%. We describe four cases of patients with IE and peripheral embolization. In this paper, we will briefly discuss the role of echocardiography, infective microorganisms and clinical aspects in the prediction of an embolic event. Therapeutic strategies are discussed.

Nitric oxide, hypoxia and brain inflammation

NO (nitric oxide) acutely and potently inhibits mitochondrial cytochrome oxidase in competition with oxygen, thereby raising the apparent K(M) for oxygen of mitochondria and neurons into the physiological or pathological range. We find that NO from an NO donor or glial inducible NOS (nitric oxide synthase) highly sensitizes neurons to hypoxia-induced death, probably via the NO-oxygen competition at cytochrome oxidase. Thus the NO from neuronal NOS during excitotoxicity or the NO from inducible NOS during inflammation may sensitize the brain to hypoxic/ischaemic damage.