Do stroke services still show sex differences? A multicenter study.

BACKGROUND: The issue of sex differences in stroke has gained concern in the past few years. However, multicenter studies are still required in this field. This study explores sex variation in a large number of patients and compares stroke characteristics among women in different age groups and across different countries. METHODS: This multicenter retrospective cross-sectional study aimed to compare sexes regarding risk factors, stroke severity, quality of services, and stroke outcome. Moreover, conventional risk factors in women according to age groups and among different countries were studied. RESULTS: Eighteen thousand six hundred fifty-nine patients from 9 countries spanning 4 continents were studied. The number of women was significantly lower than men, with older age, more prevalence of AF, hypertension, and dyslipidemia. Ischemic stroke was more severe in women, with worse outcomes among women (p: < 0.0001), although the time to treatment was shorter. Bridging that was more frequent in women (p:0.002). Analyzing only women: ischemic stroke was more frequent among the older, while hemorrhage and TIA prevailed in the younger and stroke of undetermined etiology. Comparison between countries showed differences in age, risk factors, type of stroke, and management. CONCLUSION: We observed sex differences in risk factors, stroke severity, and outcome in our population. However, access to revascularization was in favor of women.

Efficacy and safety of decompressive craniectomy in acute ischemic stroke patients treated with intravenous thrombolysis.

INTRODUCTION: The optimal timing for decompressive hemicraniectomy (DHC) after intravenous thrombolysis (IVT) remains unclear. This study in patients with acute ischemic stroke treated with IVT aimed to assess the safety of DHC and patient outcome. METHODS: Data was extracted from the Tabriz stroke registry from June 2011 up to September 2020. In all, 881 patients were treated with IVT. Among these, 23 patients underwent DH. Six patients were excluded due to symptomatic intracranial hemorrhage (parenchymal hematoma type 2 based on SITS-MOST definition) after IVT, but other types of bleeding after venous thrombolysis, including HI1, HI2, and PH1 were not excluded; so the remaining 17 patients were enrolled in the study. Functional Outcome was defined as the proportion of patients who achieved mRS score of 2-3 (moderate disability), 4-5 (severe disability), or 6 (mortality) at 90 days after stroke. mRSwas assess by trained neurologist at the hospital clinic with direct interview Safety outcome was assessed by comparison of two scans just prior to and after craniectomy. Any new hemorrhage or worsening of previous hemorrhage was reported. Parenchymal hematoma type 2, based on ECASS II definition, was considered as major surgical complication. This study was approved by the local ethics committee of the Tabriz University of Medical Sciences (Ethics Code: IR.TBZMED.REC.1398.420). RESULTS: At the three-month mRS follow up, six patients (35%) had moderate and five (29%) had severe disability. The outcome of death was observed in six patients (35%).Nine of 15 patients (60%) underwent surgery in the first 48 hours after onset of symptoms. No patient over 60 years of age survived to the three-month follow up; 67% of those who were under60 years and underwent DH in the first 48 hours had favorable outcome. Hemorrhagic complication was seen in 64% of patients but none was major. CONCLUSION: Results of this study showed that the rate of major bleeding and outcome of acute ischemic stroke patients who underwent DHC after IVT is comparable with the reported data in the literature and intentionally waiting for the fibrinolytic effects of IVT to disappear may not outweigh the benefits of DHC. Although the findings of the study should be interpreted with caution and larger studies are needed to confirm the results.

CNN-Res: deep learning framework for segmentation of acute ischemic stroke lesions on multimodal MRI images.

BACKGROUND: Accurate segmentation of stroke lesions on MRI images is very important for neurologists in the planning of post-stroke care. Segmentation helps clinicians to better diagnose and evaluation of any treatment risks. However, manual segmentation of brain lesions relies on the experience of neurologists and is also a very tedious and time-consuming process. So, in this study, we proposed a novel deep convolutional neural network (CNN-Res) that automatically performs the segmentation of ischemic stroke lesions from multimodal MRIs. METHODS: CNN-Res used a U-shaped structure, so the network has encryption and decryption paths. The residual units are embedded in the encoder path. In this model, to reduce gradient descent, the residual units were used, and to extract more complex information in images, multimodal MRI data were applied. In the link between the encryption and decryption subnets, the bottleneck strategy was used, which reduced the number of parameters and training time compared to similar research. RESULTS: CNN-Res was evaluated on two distinct datasets. First, it was examined on a dataset collected from the Neuroscience Center of Tabriz University of Medical Sciences, where the average Dice coefficient was equal to 85.43%. Then, to compare the efficiency and performance of the model with other similar works, CNN-Res was evaluated on the popular SPES 2015 competition dataset where the average Dice coefficient was 79.23%. CONCLUSION: This study presented a new and accurate method for the segmentation of MRI medical images using a deep convolutional neural network called CNN-Res, which directly predicts segment maps from raw input pixels.

Psychometric properties of the Persian version of neurogenic bladder symptom score questionnaire: A methodological study on patients with multiple sclerosis and stroke.

OBJECTIVES: Concerning the impact of neurogenic lower urinary tract dysfunction (NLUTD) on quality of life, besides the lack of standard psychometrically-analyzed Persian tools, the present study investigated the validity and reliability of the Persian version of the neurogenic bladder symptom score (NBSS) questionnaire. METHODS: A total of 279 multiple sclerosis (MS) or stroke/cerebrovascular accident (CVA) patients over 18 years of age with NLUTD referred to the neurology clinics entered the study in 2021-2022. After translation, back-translation, and developing a Persian version, its validity and reliability were determined. The content validity index (CVI) and content validity ratio (CVR) were calculated quantitatively. To determine the internal consistency and scale reliability, a test-retest was used. RESULTS: The Cronbach's α coefficient was 0.83 and the intraclass correlation coefficient (95% confidence interval) was 0.85 (0.82, 0.88). Cronbach's α in all domains (incontinence, storage and voiding, and consequence) was greater than 0.70. The criterion validity also showed a positive correlation of NBSS with the International Consultation on Incontinence Questionnaire-overactive bladder (p < 0.001 and r = 0.55). The face validity was acceptable according to the opinion of 10 participants. To determine the CVI and the CVR, 10 experts' panels reviewed all items related to the questionnaire in terms of necessity, clarity, transparency, and relevancy. Based on the expert panel all NBSS criteria got a high score, and all criteria were essential to assess NLUTD (CVI: 0.78-1). CONCLUSIONS: Regarding validity and reliability, the Persian version NBSS questionnaire can properly evaluate NLUTD in MS or stroke/CVA patients.

Did COVID-19 impact stroke services? A multicenter study.

BACKGROUND: It has been reported that acute stroke services were compromised during COVID-19 due to various pandemic-related issues. We aimed to investigate these changes by recruiting centers from different countries. METHODS: Eight countries participated in this cross-sectional, observational, retrospective study by providing data from their stroke data base. We compared 1 year before to 1 year during COVID-19 as regards onset to door (OTD), door to needle (DTN), door to groin (DTG), duration of hospital stay, National Institute of Health Stroke Scale (NIHSS) at baseline, 24 h, and at discharge as well as modified Rankin score (mRS) on discharge and at 3 months follow-up. RESULTS: During the pandemic year, there was a reduction in the number of patients, median age was significantly lower, admission NIHSS was higher, hemorrhagic stroke increased, and OTD and DTG showed no difference, while DTN time was longer, rtPA administration was decreased, thrombectomy was more frequent, and hospital stay was shorter. mRS was less favorable on discharge and at 3 months. CONCLUSION: COVID-19 showed variable effects on stroke services. Some were negatively impacted as the number of patients presenting to hospitals, DTN time, and stroke outcome, while others were marginally affected as the type of management.

Intranasal administration of mitochondria alleviated cognitive impairments and mitochondrial dysfunction in the photothrombotic model of mPFC stroke in mice.

OBJECTIVES: Dysfunction in mitochondrial activity may have profound role in ischemic stroke-induced neuronal death, hence maintaining the mitochondrial function seems to be valuable for neuronal viability and neurological improvement. METHODS: C57BL/6J mice were allocated into sham and stroke groups. Mice in the stroke groups underwent photothrombosis-induced stroke in the medial prefrontal cortex (mPFC) and were divided into the following subgroups; RB, Mito 85, Mito 170, and Mito 340, and received their respective treatments via intra-nasal route every other day (3 days per week) for one week. A battery of behavioral tests including social interaction, passive avoidance, and the Lashley III maze was used to investigate social, contextual, and spatial memories. Moreover, changes in mitochondrial function, including reactive oxygen species (ROS) and ATP levels, and mitochondrial membrane potential, were assessed in mPFC. The expression of growth-associated protein 43 (GAP-43), post-synaptic density-95 (PSD-95), and synaptophysin (SYP) was detected by western blotting. RESULTS: Behavioral results revealed that mitotherapy alleviated ischemia-induced memory impairment. Also, transplantation of exogenous mitochondria lowered ROS, restored ATP generation, and improved mitochondrial membrane potential. Induction of ischemia decreased the levels of synaptic markers in mPFC while exogenous mitochondria (170 and 340µg) significantly upregulated the expression of GAP-43 and PSD-95 after ischemic stroke. CONCLUSION: Our research highlighted the importance of mitotherapy in regulating synaptic markers expression and mitochondria function, which could represent a potential strategy for improving cognitive and memory deficits following stroke.

Cerebrolysin® and Environmental Enrichment, Alone or in Combination, Ameliorate Anxiety- and Depressive-Like Behaviors in a Post-Ischemic Depression Model in Mice.

OBJECTIVES: This study examined the beneficial effects of cerebrolysin (CBL) and enriched environment (EE), alone or in combination, on the neurobehavioral and molecular changes in the post-ischemic depression (PID) model in mice. MATERIALS AND METHODS: PID was induced in male Balb/c mice (25-30 g) by combining the transient bilateral common carotid artery occlusion (bCCAO), twice for 5 min at the interval of 10 min, with spatial restraint stress (2 h/day) for 2 weeks, started 48 h following the establishment of bCCAO model. Animals in the treatment groups received CBL (2.5 ml/kg) and/or were housed in EE (2 h/day) for two weeks. Anxiety- and depressive-like behaviors and sociability were evaluated the day after the last experiment. Changes in the serum corticosterone level, the hippocampal oxidative stress status, inflammatory cytokines, brain-derived neurotrophic factor (BDNF), and phosphorylated cAMP response element-binding protein (p-CREB)/CREB ratio were also detected. RESULTS: PID model induced anxiety- and depressive-like behaviors and impaired social behavior. These behavioral changes were accompanied by increased serum corticosterone level, increased lipid peroxidation, decreased antioxidant enzyme activities, reduced BDNF levels and p-CREB/CREB ratio, and increased protein levels of NF-κB and Iba-1 in the hippocampus. However, treatment with CBL and/or EE reversed behavioral and molecular changes induced by PID. CONCLUSION: Our findings imply that the model mimics many manifestations of human PID, and CBL and EE treatments, separately or in combination, are beneficial in reducing anxiety- and- depressive-like behaviors in this model.

Burden of tension-type headache in the Middle East and North Africa region, 1990-2019.

INTRODUCTION: Tension-type headache (TTH) is the most prevalent neurological disorder. As there is a gap in the literature regarding the disease burden attributable to TTH in the Middle East and North Africa (MENA) region, the aim of the present study was to report the epidemiological indicators of TTH in MENA, from 1990 to 2019, by sex, age and socio-demographic index (SDI). METHODS: Publicly available data on the point prevalence, annual incidence and years lived with disability (YLDs) were retrieved from the global burden of disease (GBD) 2019 study for the 21 countries and territories in MENA, between 1990 and 2019. The results were presented with numbers and age-standardised rates per 100000 population, along with their corresponding 95% uncertainty intervals (UIs). RESULTS: In 2019, the age-standardised point prevalence and annual incidence rates for TTH in the MENA region were 24504.5 and 8680.1 per 100000, respectively, which represents a 2.0% and a 0.9% increase over 1990-2019, respectively. The age-standardised YLD rate of TTH in this region in 2019 was estimated to be 68.1 per 100000 population, which has increased 1.0% since 1990. Iran [29640.4] had the highest age-standardised point prevalence rate for TTH, while Turkey [21726.3] had the lowest. In 2019, the regional point prevalence of TTH was highest in the 35-39 and 70-74 age groups, for males and females, respectively. Furthermore, the number of prevalent cases was estimated to be highest in those aged 35-39 and 25-29 years, in both males and females, respectively. Moreover, the burden of TTH was not observed to have a clear association with SDI. CONCLUSIONS: While the prevalence of TTH in the MENA region increased from 1990 to 2019, the incidence rate did not change. In addition, the burden of TTH in MENA was higher than at the global level for both sexes and all age groups. Therefore, prevention of TTH would help alleviate the attributable burden imposed on the hundreds of millions of people suffering from TTH around the region.

SARS-CoV-2 and Stroke Characteristics: A Report From the Multinational COVID-19 Stroke Study Group.

[Figure: see text].

Subjective global assessment of malnutrition and dysphagia effect on the clinical and Para-clinical outcomes in elderly ischemic stroke patients: a community-based study.

BACKGROUND: Malnutrition as a result of insufficient intake or uptake of nutrition leads to increasing rate of chronic diseases such as stroke. Stroke is one of the most common causes of death in western countries and its increasing trend has attracted lots of attention. In this regard, it seems logical to focus on modifiable risk factors such as nutrition, in order to reduce the resulting complications. Accordingly, this study aimed at evaluating nutrition status of stroke patients to estimate its relationship with clinical outcomes of stroke. METHODS: In the present cross-sectional study, 349 patients were recruited. Nutrition assessment was performed using Patient-Generated Subjective Global Assessment (PG-SGA). In addition, National Institutes of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS), and biochemical tests were performed. RESULTS: Our findings elucidated a significant positive correlation of mRS with PG-SGA and consciousness score, as well as a negative correlation with BMI, calf circumference, mid-arm circumference, and triceps skinfold at admission time (P ≤ 0.002). Moreover, a direct correlation was found between mRS and PG-SGA and consciousness score at discharge time (P ≤ 0.001). In contrast, an inverse correlation was established between mRS and mid-arm circumference (P = 0.02). Furthermore, univariate analysis indicated significant associations between mRS ≥ 3 and age (OR: 1.02; 95%CI: 1.00-1.04), PG-SGA (OR: 1.08; 95%CI: 1.03-1.13), NIHSS (OR: 1.04; 95%CI: 1.02-1.07), dysphagia (OR: 1.69; 95%CI: 1.03-2.77), consciousness (OR: 1.48; 95%CI: 1.07-2.04), and mid-arm circumference (OR: 0.95; 95%CI: 0.90-1.00). In addition, these associations remained significant in multivariate analysis for PG-SGA (OR: 1.07; 95%CI: 1.00-1.13) and NIHSS (OR: 1.04; 95%CI: 1.01-1.07). CONCLUSION: This study revealed a positive correlation between mRS and consciousness status and PG-SGA score, as well as a negative one between mRS and MAC at discharge time.

Safety and Outcomes of Intravenous Thrombolytic Therapy in Ischemic Stroke Patients with COVID-19: CASCADE Initiative.

BACKGROUND: There is little information regarding the safety of intravenous tissue plasminogen activator (IV-tPA) in patients with stroke and COVID-19. METHODS: This multicenter study included consecutive stroke patients with and without COVID-19 treated with IV-tPA between February 18, 2019, to December 31, 2020, at 9 centers participating in the CASCADE initiative. Clinical outcomes included modified Rankin Scale (mRS) at hospital discharge, in-hospital mortality, the rate of hemorrhagic transformation. Using Bayesian multiple regression and after adjusting for variables with significant value in univariable analysis, we reported the posterior adjusted odds ratio (OR, with 95% Credible Intervals [CrI]) of the main outcomes. RESULTS: A total of 545 stroke patients, including 101 patients with COVID-19 were evaluated. Patients with COVID-19 had a more severe stroke at admission. In the study cohort, 85 (15.9%) patients had a hemorrhagic transformation, and 72 (13.1%) died in the hospital. After adjustment for confounding variables, discharge mRS score ≥2 (OR: 0.73, 95% CrI: 0.16, 3.05), in-hospital mortality (OR: 2.06, 95% CrI: 0.76, 5.53), and hemorrhagic transformation (OR: 1.514, 95% CrI: 0.66, 3.31) were similar in COVID-19 and non COVID-19 patients. High-sensitivity C reactive protein level was a predictor of hemorrhagic transformation in all cases (OR:1.01, 95%CI: 1.0026, 1.018), including those with COVID-19 (OR:1.024, 95%CI:1.002, 1.054). CONCLUSION: IV-tPA treatment in patients with acute ischemic stroke and COVID-19 was not associated with an increased risk of disability, mortality, and hemorrhagic transformation compared to those without COVID-19. IV-tPA should continue to be considered as the standard of care in patients with hyper acute stroke and COVID-19.

Epidemiology of multimorbidity in Iran: An investigation of a large pharmacy claims database.

PURPOSE: Multimorbidity (MM) (presence of more than one chronic condition within a same patient) imposes a heavy burden on patients and health care systems. In contrast to high-income countries, the epidemiology of this phenomenon is unclear in low- and middle-income countries, particularly among Iranian population. METHODS: This was a retrospective cohort study using Iranian Health Insurance Organization claims database. A framework was developed for identifying a set of 18 chronic conditions from the pharmacy claims data in Iran. All 2013 outpatient utilizers (aged 18 years or older) were included. Data were analyzed according to number of chronic conditions, gender, and age. The association between MM and utilizations of health services was examined for 2013 to 2016. RESULTS: In total, 481 733 people were included. Cardiovascular diseases (including hypertension) (19.1%), depression/anxiety/sleep disorders (13.7%), and acid-related disorders (10.3%) were the three most prevalent conditions. MM was present in 21.1%. Although prevalence of MM is higher in older age groups and was present in 40% of individuals aged 65 and older, the absolute number of multimorbid patients was higher in those younger than 65 years (66 271 vs 35 386). MM was more prevalent among women (22.1%) compared with men (19.5). After multivariate adjustment for age group and sex, each additional chronic condition was associated with an increase of 2.23 physician visits, 2.86 drugs dispensed, 2.32 laboratory tests, and 1.6 medical imaging. CONCLUSIONS: Our findings challenge the current single-disease-based assumption implicit in Iranian health care system. To take account of MM, complementary strategies should be designed and implement in health care system.

Current Recommendations for the Management of Stroke Patients in the Middle East in the Era of COVID-19 Pandemic; Statement from the MENA SINO.

COVID-19 pandemic has led to a change in the way we manage acute medical illnesses. This pandemic had a negative impact on stroke care worldwide. The World Stroke Organization (WSO) has raised concerns due to the lack of available care and compromised acute stroke services globally. The numbers of thrombolysis and thrombectomy therapies are declining. As well as, the rates and door-to treatment times for thrombolysis and thrombectomy therapies are increasing. The stroke units are being reallocated to serve COVID-19 patients, and stroke teams are being redeployed to COVID-19 centers. Covid 19 confirmed cases and deaths are rising day by day. This pandemic clearly threatened and threatening all stroke care achievements regionally. Managing stroke patients during this pandemic is even more challenging at our region. The Middle East and North Africa Stroke and Interventional Neurotherapies Organization (MENA-SINO) is the main stroke organization regionally. MENA-SINO urges the need to developing new strategies and recommendations for stroke care during this pandemic. This will require multiple channels of interventions and create a protective code stroke with fast triaging path. Developing and expanding the tele-stroke programs are urgently required. There is an urgent need for enhancing collaboration and cooperation between stroke expertise regionally and internationally. Integrating such measures will inevitably lead to an improvement and upgrading of the services to a satisfactory level.

Targeting pericytes for neurovascular regeneration.

Pericytes, as a key cellular part of the blood-brain barrier, play an important role in the maintenance of brain neurovascular unit. These cells participate in brain homeostasis by regulating vascular development and integrity mainly through secreting various factors. Pericytes per se show different restorative properties after blood-brain barrier injury. Upon the occurrence of brain acute and chronic diseases, pericytes provoke immune cells to regulate neuro-inflammatory conditions. Loss of pericytes in distinct neurologic disorders intensifies blood-brain barrier permeability and leads to vascular dementia. The therapeutic potential of pericytes is originated from the unique morphological shape, location, and their ability in providing vast paracrine and juxtacrine interactions. A subset of pericytes possesses multipotentiality and exhibit trans-differentiation capacity in the context of damaged tissue. This review article aimed to highlight the critical role of pericytes in restoration of the blood-brain barrier after injury by focusing on the dynamics of pericytes and cross-talk with other cell types.

Impact of Premorbid Malnutrition and Dysphagia on Ischemic Stroke Outcome in Elderly Patients: A Community-Based Study.

OBJECTIVE: The present study was performed to assess nutritional status and its relationship with clinical outcomes in elderly stroke patients. METHOD: In this cross-sectional study, 253 stroke patients were studied. Mini Nutritional Assessment (MNA) was used to assign patients to three groups: malnourished, at risk of malnutrition, and well nourished. Northwestern Dysphagia Patient Check Sheet was administered to all patients. Anthropometric measures, including body mass index (BMI), calf circumferences (CC), mid-arm circumferences (MAC), and triceps skinfold thickness were brought out. In addition, National Institutes of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS), and biochemical tests were performed. RESULTS: Of 253 patients, 34.4% were malnourished, 42.3% were at risk of malnutrition, and 23.3% were well nourished. The malnourished patients had significantly lower BMI, CC, and MAC (p < 0.05). The levels of albumin and high-sensitivity C-reactive protein were significantly different among the groups (p < 0.001). The admission and 3-month follow-up mRS scores, as well as dysphagia, were significantly higher in the malnourished patients and those at risk of malnutrition (p < 0.001). In addition, mRS scores at admission and 3-month follow-up scores, as well as the length of hospital stay (LOS), were significantly correlated with MNA score, dysphagia, BMI, CC, MAC, albumin, and high-sensitivity C-reactive protein (p < 0.05). Significant unadjusted associations were observed among MNA scores, BMI, CC, MAC, dysphagia scores, NIHSS scores, length of hospital stay (LOS), albumin, hs-C-reactive protein (hs-CRP), and erythrocyte sedimentation rate (ESR) with a poor outcome. With a multivariate logistic regression analysis, NIHSS scores and MNA scores remained significantly associated with the poor outcome in patients with ischemic stroke. CONCLUSIONS: The findings of the present study underline the importance of nutritional status in elderly stroke patients.

Cognitive Rehabilitation Improves Ischemic Stroke-Induced Cognitive Impairment: Role of Growth Factors.

Cognitive dysfunction is the most common nonphysical impairment in the stroke survivors. This impairment has a negative impact on patients' quality of life affects their daily living activities. Both pharmacological and nonpharmacological interventions are employed to improve cognitive impairment. Recently, nonpharmacological interventions have attracted great attention. Cognitive rehabilitation is considered as a therapeutic strategy to improve and maintain cognitive skills in patients with stroke. Enriched environment (EE), as a cognitive rehabilitation strategy, has been shown to facilitate physical, cognitive, as well as social abilities. Moreover, EE has been shown to increase endogenous growth factors. Growth factors have pivotal role in neurogenesis, synaptogenesis, as well as brain remodeling through neuron development, differentiation, and survival. In addition, administration of exogenous growth factors prevents cognitive dysfunction. Here, we review preclinical and clinical evidence of cognitive rehabilitation and role of growth factors in treating poststroke cognitive impairment.

The interplay of microRNAs and post-ischemic glutamate excitotoxicity: an emergent research field in stroke medicine.

Stroke is the second leading cause of death and the most common cause of adult disabilities among elderlies. It involves a complex series of mechanisms among which, excitotoxicity is of great importance. Also, miRNAs appear to play role in post-stroke excitotoxicity, and changes in their transcriptome occur right after cerebral ischemia. Recent data indicate that specific miRNAs such as miRNA-223, miRNA-181, miRNA-125a, miRNA-125b, miRNA-1000, miRNA-132 and miRNA-124a regulate glutamate neurotransmission and excitotoxicity during stroke. However, limitations such as poor in vivo stability, side effects and inappropriate biodistribution in miRNA-based therapies still exist and should be overcome before clinical application. Thence, investigation of the effect of application of these miRNAs after the onset of ischemia is a pivotal step for manipulating these miRNAs in clinical use. Given this, present review concentrates on miRNAs roles in post-ischemic stroke excitotoxicity.

Toxoplasmosis and Alzheimer: can Toxoplasma gondii really be introduced as a risk factor in etiology of Alzheimer?

Alzheimer is a progressive neurological disease that results in irreversible loss of neurons and includes about two thirds of all cases of dementia. Toxoplasma gondii may be an important infectious agent involved in neurodegenerative diseases. The aim of this study was to investigate the correlation between Toxoplasma as an etiologic agent in the progress of Alzheimer's disease. This case control study was conducted on 75 Alzheimer's patients and 75 healthy volunteers. Blood samples were obtained and anti-Toxoplasma IgG and IgM tests were done by using ELISA technique. DNA was extracted from buffy coat and then GRA6 gene and SAG2 loci were amplified by PCR and nested PCR, respectively. Chi-square, Fisher's test, and binary logistic regression were used for data analysis. A percentage of 61.3 % of Alzheimer's patients and 62.6 % of healthy volunteers were positive for anti-Toxoplasma IgG but all participants were negative for anti-Toxoplasma IgM. There were no significant differences between Alzheimer's patients with their controls in terms of anti-Toxoplasma IgG antibody (P = 0.5). Due to lack of positive IgM sample, results of the molecular methods were negative by GRA6 and SAG2 fragments amplification. This result shows that, infection with T. gondii cannot be considered as a risk factor for etiology and developing Alzheimer's disease.

Amyloid-beta: a crucial factor in Alzheimer's disease.

Alzheimer's disease (AD) is the most prevalent form of dementia which affects people older than 60 years of age. In AD, the dysregulation of the amyloid-beta (Aß) level leads to the appearance of senile plaques which contain Aß depositions. Aß is a complex biological molecule which interacts with many types of receptors and/or forms insoluble assemblies and, eventually, its nonphysiological depositions alternate with the normal neuronal conditions. In this situation, AD signs appear and the patients experience marked cognitional disabilities. In general, intellect, social skills, personality, and memory are influenced by this disease and, in the long run, it leads to a reduction in quality of life and life expectancy. Due to the pivotal role of Aß in the pathobiology of AD, a great deal of effort has been made to reveal its exact role in neuronal dysfunctions and to finding efficacious therapeutic strategies against its adverse neuronal outcomes. Hence, the determination of its different molecular assemblies and the mechanisms underlying its pathological effects are of interest. In the present paper, some of the well-established structural forms of Aß, its interactions with various receptors and possible molecular and cellular mechanisms underlying its neurotoxicity are discussed. In addition, several Aß-based rodent models of AD are reviewed.