Microstructure investigation on barrier shapes of double barrier magnetic tunnel junctions

Barrier shapes and its detailed microstructures in the double barrier magnetic tunnel junctions were intensively investigated by both high resolution transmission electron microscopy and electron holography. Two broad (>2 nm) potential wells (i.e., shapes of AlOx layers) with slanted interfaces were observed in the electron hologram of the as-deposited samples. However, in the hologram of the annealed samples, two narrowed (down to 1.18 nm) and almost equal (height) potential wells with sharp and steep interfaces were acquired. This indicates that the value of tunnel magnetoresistance can be increased from 12.8% to 29.4% at room temperature by annealing treatment where the sharpness and height of the barriers played a critical rol

Lymph node-derived donor encephalitogenic CD4+ T cells in C57BL/6 mice adoptive transfer experimental autoimmune encephalomyelitis highly express GM-CSF and T-bet

Experimental autoimmune encephalomyelitis (EAE) is a relevant animal model for the human demyelinating inflammatory disorder of the central nervous system (CNS), multiple sclerosis (MS). Induction of EAE by adoptive transfer allows studying the role of the donor T lymphocyte in disease pathogenesis. It has been challenging to reliably induce adoptive transfer EAE in C57BL/6 (H-2b) mice. The goal of this study was to develop a reproducible and high yield protocol for adoptive transfer EAE in C57BL/6 mice. A step-wise experimental approach permitted us to develop a protocol that resulted in a consistent relatively high disease incidence of ~70% in recipient mice. Donor mice were immunized with myelin oligodendrocyte glycoprotein (MOG)p35-55 in complete Freund's adjuvant (CFA) followed by pertussis toxin (PT). Only lymph node cells (LNC) isolated at day 12 post immunization, and restimulated in vitro for 72 hours with 10 μg/mL of MOGp35-55 and 0.5 ng/mL of interleukin-12 (IL-12) were able to transfer disease. The ability of LNC to transfer disease was associated with the presence of inflammatory infiltrates in the CNS at day 12. Interferon gamma (IFNγ) was produced at comparable levels in cell cultures prepared from mice at both day 6 and day 12 post immunization. By contrast, there was a trend towards a negative association between IL-17 and disease susceptibility in our EAE model. The amount of GM-CSF secreted was significantly increased in the culture supernatants from cells collected at day 12 post immunization versus those collected at day 6 post-immunization. Activated CD4+ T cells present in the day 12 LNC cultures maintained expression of the transcription factor T-bet, which has been shown to regulate the expression of the IL-23 receptor. Also, there was an increased prevalence of MOGp35-55-specific CD4+ T cells in day 12 LNC after in vitro re-stimulation. In summary, encephalitogenic LNC that adoptively transfer EAE in C57BL/6 mice were not characterized by a single biomarker in our study, but by a composite of inflammatory markers. Our data further suggest that GM-CSF expression by CD4+ T cells regulated by IL-23 contributes to their encephalitogenicity in our EAE model

Primitive homochiral polyester formation driven by tartaric acid and calcium availability

α-hydroxy acids (αHAs), simple and prebiotically plausible organic monomers, were likely present in various environments on and off Earth and could have played a role in directing the emergence of the first homochiral living systems. Some αHAs, which could have been of varying chirality, can undergo dehydration polymerization into polyesters, which could assemble into membraneless microdroplets upon rehydration; understanding these processes is critical for unraveling how simple prebiotic molecules transitioned into more complex systems capable of supporting selective chemical reactions, a key step toward the origin of life. Here, we focused on tartaric acid (TA), a prebiotically relevant αHA with multiple chiral forms, to probe plausible mechanisms by which primitive αHA and polyester-based systems could have participated in selective homochiral polymer synthesis. Enantiopure solutions of d-TA or l-TA polymerize efficiently via dehydration, while racemic dl-TA polymerization is inhibited due to stereochemical incompatibility. We found that Ca2+ ions influence this process in two significant ways: 1) regulating TA monomer availability through selective crystallization, removing equal amounts of both enantiomers in racemic proportion and thereby enriching the enantiomeric excess of the remaining nonracemic TA solution; and 2) modulating polymerization by suppressing enantiopure TA polymerization while enabling dl-TA polymerization. These findings suggest that the differential availability of simple inorganic ions, such as Ca2+, could have indirectly mediated the selection of simple organic chiral monomers and the emergence of homochirality in primitive protocell-forming polymers, offering a pathway from nonliving to living matter in early Earth environments

CD11c+ CD88+ CD317+ myeloid cells are critical mediators of persistent CNS autoimmunity

Natalizumab, a humanized monoclonal antibody (mAb) against α4-integrin, reduces the number of dendritic cells (DC) in cerebral perivascular spaces in multiple sclerosis (MS). Selective deletion of α4-integrin in CD11c+ cells should curtail their migration to the central nervous system (CNS) and ameliorate experimental autoimmune encephalomyelitis (EAE). We generated CD11c.Cre+/−ITGA4fl/fl C57BL/6 mice to selectively delete α4-integrin in CD11c+ cells. Active immunization and adoptive transfer EAE models were employed and compared with WT controls. Multiparameter flow cytometry was utilized to immunophenotype leukocyte subsets. Single-cell RNA sequencing was used to profile individual cells. α4-Integrin expression by CD11c+ cells was significantly reduced in primary and secondary lymphoid organs in CD11c.Cre+/−ITGA4fl/fl mice. In active EAE, a delayed disease onset was observed in CD11c.Cre+/−ITGA4fl/fl mice, during which CD11c+CD88+ cells were sequestered in the blood. Upon clinical EAE onset, CD11c+CD88+ cells appeared in the CNS and expressed CD317+. In adoptive transfer experiments, CD11c.Cre+/−ITGA4fl/fl mice had ameliorated clinical disease phenotype associated with significantly diminished numbers of CNS CD11c+CD88+CD317+ cells. In human cerebrospinal fluid from subjects with neuroinflammation, microglia-like cells display coincident expression of ITGAX (CD11c), C5AR1 (CD88), and BST2 (CD317). In mice, we show that only activated, but not naïve microglia expressed CD11c, CD88, and CD317. Finally, anti-CD317 treatment prior to clinical EAE substantially enhanced recovery in mice

Gene Targeting Implicates Cdc42 GTPase in GPVI and Non-GPVI Mediated Platelet Filopodia Formation, Secretion and Aggregation

Background: Cdc42 and Rac1, members of the Rho family of small GTPases, play critical roles in actin cytoskeleton regulation. We have shown previously that Rac1 is involved in regulation of platelet secretion and aggregation. However, the role of Cdc42 in platelet activation remains controversial. This study was undertaken to better understand the role of Cdc42 in platelet activation. Methodology/Principal Findings: We utilized the Mx-cre;Cdc42 lox/lox inducible mice with transient Cdc42 deletion to investigate the involvement of Cdc42 in platelet function. The Cdc42-deficient mice exhibited a significantly reduced platelet count than the matching Cdc42 +/+ mice. Platelets isolated from Cdc42 2/2, as compared to Cdc42 +/+, mice exhibited (a) diminished phosphorylation of PAK1/2, an effector molecule of Cdc42, (b) inhibition of filopodia formation on immobilized CRP or fibrinogen, (c) inhibition of CRP- or thrombin-induced secretion of ATP and release of P-selectin, (d) inhibition of CRP, collagen or thrombin induced platelet aggregation, and (e) minimal phosphorylation of Akt upon stimulation with CRP or thrombin. The bleeding times were significantly prolonged in Cdc42 2/2 mice compared with Cdc42 +/+ mice. Conclusion/Significance: Our data demonstrate that Cdc42 is required for platelet filopodia formation, secretion an

A Novel Small Molecule 1,2,3,4,6-penta-O-galloyl-α-D-glucopyranose Mimics the Antiplatelet Actions of Insulin

BACKGROUND: We have shown that 1,2,3,4,6-penta-O-galloyl-α-D-glucopyranose (α-PGG), an orally effective hypoglycemic small molecule, binds to insulin receptors and activates insulin-mediated glucose transport. Insulin has been shown to bind to its receptors on platelets and inhibit platelet activation. In this study we tested our hypothesis that if insulin possesses anti-platelet properties then insulin mimetic small molecules should mimic antiplatelet actions of insulin. PRINCIPAL FINDINGS: Incubation of human platelets with insulin or α-PGG induced phosphorylation of insulin receptors and IRS-1 and blocked ADP or collagen induced aggregation. Pre-treatment of platelets with α-PGG inhibited thrombin-induced release of P-selectin, secretion of ATP and aggregation. Addition of ADP or thrombin to platelets significantly decreased the basal cyclic AMP levels. Pre-incubation of platelets with α-PGG blocked ADP or thrombin induced decrease in platelet cyclic AMP levels but did not alter the basal or PGE(1) induced increase in cAMP levels. Addition of α-PGG to platelets blocked agonist induced rise in platelet cytosolic calcium and phosphorylation of Akt. Administration of α-PGG (20 mg kg(-1)) to wild type mice blocked ex vivo platelet aggregation induced by ADP or collagen. CONCLUSIONS: These data suggest that α-PGG inhibits platelet activation, at least in part, by inducing phosphorylation of insulin receptors leading to inhibition of agonist induced: (a) decrease in cyclic AMP; (b) rise in cytosolic calcium; and (c) phosphorylation of Akt. These findings taken together with our earlier reports that α-PGG mimics insulin signaling suggest that inhibition of platelet activation by α-PGG mimics antiplatelet actions of insulin

Pharmacological prion protein silencing accelerates central nervous system autoimmune disease via T cell receptor signalling

The primary biological function of the endogenous cellular prion protein has remained unclear. We investigated its biological function in the generation of cellular immune responses using cellular prion protein gene-specific small interfering ribonucleic acid in vivo and in vitro. Our results were confirmed by blocking cellular prion protein with monovalent antibodies and by using cellular prion protein-deficient and -transgenic mice. In vivo prion protein gene-small interfering ribonucleic acid treatment effects were of limited duration, restricted to secondary lymphoid organs and resulted in a 70% reduction of cellular prion protein expression in leukocytes. Disruption of cellular prion protein signalling augmented antigen-specific activation and proliferation, and enhanced T cell receptor signalling, resulting in zeta-chain-associated protein-70 phosphorylation and nuclear factor of activated T cells/activator protein 1 transcriptional activity. In vivo prion protein gene-small interfering ribonucleic acid treatment promoted T cell differentiation towards pro-inflammatory phenotypes and increased survival of antigen-specific T cells. Cellular prion protein silencing with small interfering ribonucleic acid also resulted in the worsening of actively induced and adoptively transferred experimental autoimmune encephalomyelitis. Finally, treatment of myelin basic protein1–11 T cell receptor transgenic mice with prion protein gene-small interfering ribonucleic acid resulted in spontaneous experimental autoimmune encephalomyelitis. Thus, central nervous system autoimmune disease was modulated at all stages of disease: the generation of the T cell effector response, the elicitation of T effector function and the perpetuation of cellular immune responses. Our findings indicate that cellular prion protein regulates T cell receptor-mediated T cell activation, differentiation and survival. Defects in autoimmunity are restricted to the immune system and not the central nervous system. Our data identify cellular prion protein as a regulator of cellular immunological homoeostasis and suggest cellular prion protein as a novel potential target for therapeutic immunomodulation

Global, regional, and national burden of headache disorders, 1990–2023: a systematic analysis for the Global Burden of Disease Study 2023

Background: The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2023 estimates health loss from migraine, tension-type headache, and medication-overuse headache. This study presents updated results on headache-attributed burden from 1990 to 2023, along with clinical and public health implications. Methods: Data on the prevalence, incidence, or remission of migraine, tension-type headache, and medication-overuse headache were extracted from published population-based studies. We used hierarchical Bayesian meta-regression modelling to estimate global, regional, and country-level prevalence of headache disorders. For the first time in GBD 2023, age-specific and sex-specific estimates of time in symptomatic state were applied by meta-analysing individual participant data from 41 653 individuals from the general populations of 18 countries from all parts of the world. Disability weights were applied to calculate years lived with disability (YLDs). Since medication-overuse headache is a sequela of a mistreated primary headache (due to medication overuse), its burden was reattributed to migraine or tension-type headache, informed by a meta-analysis of three longitudinal studies. Findings: In 2023, 2·9 billion individuals (95% uncertainty interval 2·6–3·1) were affected by headache disorders, with a global age-standardised prevalence of 34·6% (31·6–37·5) and a YLD rate of 541·9 (373·4–739·9) per 100 000 population, with 487·5 (323·0–678·8) per 100 000 population attributed to migraine. The prevalence rates of these headache disorders have remained stable over the past three decades. YLD rates due to headache disorders were more than twice as high in females (739·9 [511·2–1011·5] per 100 000) as in males (346·1 [240·4–481·8] per 100 000). Medication-overuse headache contributed 58·9% of the YLD estimates for tension-type headache in males and 56·1% in females, as well as 22·6% of the YLD estimates for migraines in males and 14·1% in females. Interpretation: Headache disorders, in particular migraine, continue to be a major global health challenge, emphasising the need for effective management and prevention strategies. Much headache-attributed burden could be averted or eliminated by avoiding overuse of medication (including over-the-counter medication), underscoring the importance of public education