The outbreak of the novel coronavirus infectious disease 2019 (COVID-19) caused by the SARS-CoV-2 virus has rapidly spread around the world. Increasing evidence has suggested that patients with COVID-19 may present neurological symptoms, and cerebrovascular diseases are one of the most frequent comorbidities. The markedly elevated D-dimer levels in patients with acute ischemic stroke suggests that SARS-CoV-2 infection may induce an inflammatory response and trigger a hypercoagulation state, thus leading to acute ischemic stroke. Cardioembolism and atherosclerosis in patients with COVID-19 infection may also increase the risk of ischemic stroke. The reduction of the angiotensin-converting enzyme II (ACE2) caused by SARS-CoV-2 binding to the ACE2 receptor can lead to abnormally elevated blood pressure and increase the risk of hemorrhagic stroke. Additionally, the cytokine storm induced by the immune response against the viral infection increases the risk of acute stroke. The management for COVID-19 patients with stroke is not only based on the traditional guidelines, but also based on the experience and new instructions from healthcare workers worldwide who are combatting COVID-19.

Abstract

No abstract

Design variability due to die-to-die and within-die process variations

Accumulating evidence indicates that intracellular reactive oxygen species (ROS) production is highly involved in bone homeostasis by intervening osteoclast or osteoblast differentiation. Interestingly, ROS that are known as oxidizing agents exert dose-dependent biphasic properties in bone remodeling, including preventing osteoblast activity but accelerating osteoclast resorption. ROS mainly composed of superoxide anion radical, hydroxyl radical, nitric oxide, and two-electron reduction product hydrogen peroxide, which are important components to regulate bone cell metabolism and function in mammal skeleton. These free radicals can be partly produced in bone and boosted in an inflammation state. Although numerous researches have emphasized the impacts of ROS on bone cell biology and verified the mechanism of ROS signaling cascades, the recapitulatory commentary is necessary. In this review article, we particularly focus on the regulation of the intracellular ROS and its potential mechanism impacting on cell-signaling transduction in osteoclast and osteoblast differentiation for preferable understanding the pathogenesis and searching for novel therapeutic protocols for human bone diseases.

No abstract

No abstract

Diabetes mellitus is a chronic metabolic disease with a proinflammatory microenvironment, causing poor vascularization and bone regeneration. Due to the lack of effective therapy and one-sided focus on the direct angiogenic properties of biomaterials and osteogenesis stimulation, the treatment of diabetic bone defect remains challenging and complex. In this study, using gelatin methacryloyl (GelMA) as a template, a lithium (Li) -modified bioglass-hydrogel for diabetic bone regeneration is developed. It exhibits a sustained ion release for better bone regeneration under diabetic microenvironment. The hydrogel is shown to be mechanically adaptable to the complex shape of the defect. In vitro, Li-modified bioglass-hydrogel promoted cell proliferation, direct osteogenesis, and regulated macrophages in high glucose (HG) microenvironment, with the secretion of bone morphogenetic protein-2 and vascular endothelial growth factor to stimulate osteogenesis and neovascularization indirectly. In vivo, composite hydrogels containing GelMA and Li-MBG (GM/M-Li) release Li ions to relieve inflammation, providing an anti-inflammatory microenvironment for osteogenesis and angiogenesis. Applying Li-modified bioglass-hydrogel, significantly enhances bone regeneration in a diabetic rat bone defect. Together, both remarkable in vitro and in vivo outcomes in this study present an opportunity for diabetic bone regeneration on the basis of HG microenvironment.