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 (Aβ) level leads to the appearance of senile plaques which contain Aβ depositions. Aβ 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 Aβ 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 Aβ, its interactions with various receptors and possible molecular and cellular mechanisms underlying its neurotoxicity are discussed. In addition, several Aβ-based rodent models of AD are reviewed.

Objective:The objectives of this study were to measure the global impact of the pandemic on the volumes for intravenous thrombolysis (IVT), IVT transfers, and stroke hospitalizations over 4 months at the height of the pandemic (March 1 to June 30, 2020) compared with two control 4-month periods.Methods:We conducted a cross-sectional, observational, retrospective study across 6 continents, 70 countries, and 457 stroke centers. Diagnoses were identified by their ICD-10 codes and/or classifications in stroke databases.Results:There were 91,373 stroke admissions in the 4 months immediately before compared to 80,894 admissions during the pandemic months, representing an 11.5% (95%CI, -11.7 to - 11.3, p<0.0001) decline. There were 13,334 IVT therapies in the 4 months preceding compared to 11,570 procedures during the pandemic, representing a 13.2% (95%CI, -13.8 to -12.7, p<0.0001) drop. Interfacility IVT transfers decreased from 1,337 to 1,178, or an 11.9% decrease (95%CI, -13.7 to -10.3, p=0.001). Recovery of stroke hospitalization volume (9.5%, 95%CI 9.2-9.8, p<0.0001) was noted over the two later (May, June) versus the two earlier (March, April) pandemic months. There was a 1.48% stroke rate across 119,967 COVID-19 hospitalizations. SARS-CoV-2 infection was noted in 3.3% (1,722/52,026) of all stroke admissions.Conclusions:The COVID-19 pandemic was associated with a global decline in the volume of stroke hospitalizations, IVT, and interfacility IVT transfers. Primary stroke centers and centers with higher COVID19 inpatient volumes experienced steeper declines. Recovery of stroke hospitalization was noted in the later pandemic months.

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Background: The COVID-19 pandemic led to profound changes in the organization of health care systems worldwide. Aims: We sought to measure the global impact of the COVID-19 pandemic on the volumes for mechanical thrombectomy (MT), stroke, and intracranial hemorrhage (ICH) hospitalizations over a 3-month period at the height of the pandemic (March 1 to May 31, 2020) compared with two control 3-month periods (immediately preceding and one year prior). Methods: Retrospective, observational, international study, across 6 continents, 40 countries, and 187 comprehensive stroke centers. The diagnoses were identified by their ICD-10 codes and/or classifications in stroke databases at participating centers. Results: The hospitalization volumes for any stroke, ICH, and MT were 26,699, 4,002, and 5,191 in the 3 months immediately before versus 21,576, 3,540, and 4,533 during the first 3 pandemic months, representing declines of 19.2% (95%CI,-19.7 to -18.7), 11.5% (95%CI,-12.6 to -10.6), and 12.7% (95%CI,-13.6 to -11.8), respectively. The decreases were noted across centers with high, mid, and low COVID-19 hospitalization burden, and also across high, mid, and low volume stroke/MT centers. High-volume COVID-19 centers (-20.5%) had greater declines in MT volumes than mid- (-10.1%) and low-volume (-8.7%) centers (p<0.0001). There was a 1.5% stroke rate across 54,366 COVID-19 hospitalizations. SARS-CoV-2 infection was noted in 3.9% (784/20,250) of all stroke admissions. Conclusion: The COVID-19 pandemic was associated with a global decline in the volume of overall stroke hospitalizations, MT procedures, and ICH admission volumes. Despite geographic variations, these volume reductions were observed regardless of COVID-19 hospitalization burden and pre-pandemic stroke/MT volumes.

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.

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Studies have shown an increase in the incidence of MS in Iran. The aim of our study was to evaluate the relationship between environmental exposure and MS in Iran. This case-control study was conducted on 660 MS patients and 421 controls. Many environmental factors are compared between the two groups. Our findings demonstrated that prematurity ([OR = 4.99 (95% CI 1.34-18.68), P = 0.017]), history of measles and mumps ([OR = 1.60 (95% CI 1.05-2.45), P = 0.029; OR = 1.85 (95% CI 1.22-2.78), P = 0.003, respectively]), breast feeding [OR = 2.90 (95% CI 1.49-5.65), P = 0.002], head trauma in childhood ([OR = 8.21 (95% CI 1.56-43.06), P = 0.013]), vaccination in adulthood ([OR = 4.57 (95% CI 1.14-18.41), P = 0.032, respectively]), migraine ([OR = 3.50 (95% CI 1.61-7.59), P = 0.002]), family history of MS, IBD, migraine, and collagen vascular diseases ([OR = 2.73 (95% CI 1.56-4.78), P < 0.001], [OR = 3.14 (95% CI 1.460-6.78), P = 0.004; OR = 3.18 (95% CI 1.83-5.53), P < 0.001; OR = 1.81 (95% CI 1.03-3.20), P = 0.040, respectively]), stressful events ([OR = 32.57 (95% CI 17.21-61.64), P < 0.001]), and microwave exposure ([OR = 3.55 (95% CI 2.24-5.63), P ≤0.001]) were more in the MS group. Sun exposure ([OR = 0.09 (95% CI 0.02-0.38), P = 0.001]), dairy and calcium consumption ([OR = 0.44 (95% CI 0.27-0.71), P = 0.001]), diabetes mellitus ([OR = 0.11 (95% CI 0.01-00.99), P = 0.049], and complete vaccination during childhood appeared to decreased MS risk. Our results investigated many risk factors and protective factors in Iran.

Background Elevated D-dimer levels are a marker of both thrombin formation and fibrinolysis. Currently D-dimer measurement is routinely used for ruling out venous thromboembolism and diagnosis/monitoring of disseminated intravascular coagulation. Recent emerging data suggest that D-dimer may become an important biomarker in ischemic stroke as well as in cardiovascular diseases. Aims To outline the clinical utility of D-dimer in work-up and management of ischemic stroke. Summary D-dimer measurement is most useful in stroke with active cancer as it can confirm etiologic diagnosis, predict recurrent stroke risk, and aid treatment decision in cancer-associated stroke. In cryptogenic stroke, high D-dimer levels can also provide clues for the cause of stroke as occult cancer and undetected cardiac embolic source as occult atrial fibrillation and may be helpful in treatment decision making of secondary stroke prevention. Serial D-dimer measurements should be further studied to monitor antithrombotic therapy effectiveness in both cardiogenic and cryptogenic etiologies. Conclusion Accumulating data suggests the utility of D-dimer test in the management of ischemic stroke, although the evidence is still limited. Future studies would clarify the role of D-dimer measurement in ischemic stroke.