Amyloid-Independent Mechanisms in Alzheimer's Disease Pathogenesis

Despite the progress of the past two decades, the cause of Alzheimer's disease (AD) and effective treatments against it remain elusive. The hypothesis that amyloid-β (Aβ) peptides are the primary causative agents of AD retains significant support among researchers. Nonetheless, a growing body of evidence shows that Aβ peptides are unlikely to be the sole factor in AD etiology. Evidence that Aβ/amyloid-independent factors, including the actions of AD-related genes, also contribute significantly to AD pathogenesis was presented in a symposium at the 2010 Annual Meeting of the Society for Neuroscience. Here we summarize the studies showing how amyloid-independent mechanisms cause defective endo-lysosomal trafficking, altered intracellular signaling cascades, or impaired neurotransmitter release and contribute to synaptic dysfunction and/or neurodegeneration, leading to dementia in AD. A view of AD pathogenesis that encompasses both the amyloid-dependent and -independent mechanisms will help fill the gaps in our knowledge and reconcile the findings that cannot be explained solely by the amyloid hypothesis.National Institutes of Health (U.S.) (Grant P01-AG027916)National Institutes of Health (U.S.) (Grant R01-NS051874

Molecular dynamics studies on the NMR and X-ray structures of rabbit prion protein wild-type and mutants

Prion diseases are invariably fatal and highly infectious neurodegenerative diseases that affect a wide variety of mammalian species such as sheep, goats, mice, humans, chimpanzees, hamsters, cattle, elks, deer, minks, cats, chicken, pigs, turtles, etc. These neurodegenerative diseases are caused by the conversion from a soluble normal cellular protein into insoluble abnormally folded infectious prions and the conversion is believed to involve conformational change from a predominantly alpha-helical protein to one rich in beta-sheet structure. Such conformational changes may be amenable to study by molecular dynamics (MD) techniques. For rabbits, classical studies show they have a low susceptibility to be infected, but in 2012 it was reported that rabbit prion can be generated (though not directly) and the rabbit prion is infectious and transmissible (Proceedings of the National Academy of Sciences USA 109(13): 5080-5). This paper studies the NMR and X-ray molecular structures of rabbit prion protein wild-type and mutants by MD techniques, in order to understand the specific mechanism of rabbit prion protein and rabbit prions.Comment: (The 2nd version of arXiv1304.7633

Management of Lithium Dosing Around Delivery:An Observational Study

OBJECTIVES: Recommendations on lithium dosing around delivery vary, with several guidelines suggesting that lithium should be discontinued prior to delivery. We aimed to evaluate the validity of these recommendations by investigating 1) maternal lithium blood level changes following delivery, and 2) the association between neonatal lithium blood levels at delivery and neonatal outcomes.METHODS: In this retrospective observational cohort study, we included women with at least one lithium blood level measurement during the final week of pregnancy and the first postpartum week. For aim 2, we included a subcohort of women with neonates for whom neonatal lithium blood levels (obtained from the umbilical cord or a neonatal vein puncture within 24 hours of delivery) were available.RESULTS: There were a total of 233 maternal lithium blood level measurements; 55 (23.6%) in the week before delivery and 178 (76.4%) in the week after. There was no association between time and lithium blood level/dose ratio (Pearson correlation coefficient -0.03, P = .63). Additionally, we included a total of 29 neonates for whom a lithium measurement was performed within 24 hours postpartum. Maternal and neonatal lithium blood levels were strongly correlated. We observed no associations between neonatal lithium blood levels at delivery and neonatal outcomes.CONCLUSION: Based on our findings, we do not recommend lowering the dosage or discontinuation of lithium prior to delivery. Stable dosing can prevent subtherapeutic lithium serum levels, which is especially important in the postpartum period when relapse risks are highest.Appeared originally in Bipolar Disord 2021; 23:49-54.</p

Identifying postpartum depression:Using key risk factors for early detection

Background: Personal and family history of psychiatric disorders are key risk factors for postpartum depression (PPD), yet their combined contribution has been understudied. Objective: To examine personal and family psychiatric history, alone and combined, and their effect on absolute risk and relative risk (RR) of mild/moderate or severe PPD. Methods: In this cohort study, we used data from 142 064 childbirths with PPD screenings from 2015 to 2021 merged with population registers. Exposures were personal and family psychiatric history defined as a psychiatric hospital contact or psychotropic prescription fills by index mothers and their parents prior to delivery. Outcomes were mild/moderate PPD (Edinburgh Postnatal Depression Scale, cut-off: ≥11 within 12 weeks post partum) and severe PPD (antidepressant fill or depression diagnosis within 6 months post partum). We calculated absolute risks and RRs using Poisson regression models adjusted for parity, education, maternal age, and calendar year. Findings: Of the 142 064 participants, 23.4% had no psychiatric history, 47.4% had only family history, 6.0% had only personal history, and 23.2% had both. The latter group had the highest risk of PPD: absolute risk of mild/moderate PPD was 11.7% (95% CI 11.5%; 11.8%), and adjusted RR: 2.35 (95% CI 2.22; 2.49). Alone, personal psychiatric history was the most potent risk factor. Dose–response relationship based on severity of personal and family psychiatric history was found. Discussion: Our study documents a substantial association between personal and family psychiatric history and PPD risk. Clinical implications: Evaluating combinations of risk factors is important to improve risk assessment.</p

Presenilin1 familial Alzheimer disease mutants inactivate EFNB1- and BDNF-dependent neuroprotection against excitotoxicity by affecting neuroprotective complexes of N-methyl-d-aspartate receptor

Excitotoxicity is thought to play key roles in brain neurodegeneration and stroke. Here we show that neuroprotection against excitotoxicity by trophic factors EFNB1 and brain-derived neurotrophic factor (called here factors) requires de novo formation of 'survival complexes' which are factor-stimulated complexes of N-methyl-D-aspartate receptor with factor receptor and presenilin 1. Absence of presenilin 1 reduces the formation of survival complexes and abolishes neuroprotection. EPH receptor B2- and N-methyl-D-aspartate receptor-derived peptides designed to disrupt formation of survival complexes also decrease the factor-stimulated neuroprotection. Strikingly, factor-dependent neuroprotection and levels of the de novo factor-stimulated survival complexes decrease dramatically in neurons expressing presenilin 1 familial Alzheimer disease mutants. Mouse neurons and brains expressing presenilin 1 familial Alzheimer disease mutants contain increased amounts of constitutive presenilin 1-N-methyl-D-aspartate receptor complexes unresponsive to factors. Interestingly, the stability of the familial Alzheimer disease presenilin 1-N-methyl-D-aspartate receptor complexes differs from that of wild type complexes and neurons of mutant-expressing brains are more vulnerable to cerebral ischaemia than neurons of wild type brains. Furthermore, N-methyl-D-aspartate receptor-mediated excitatory post-synaptic currents at CA1 synapses are altered by presenilin 1 familial Alzheimer disease mutants. Importantly, high levels of presenilin 1-N-methyl-D-aspartate receptor complexes are also found in post-mortem brains of Alzheimer disease patients expressing presenilin 1 familial Alzheimer disease mutants. Together, our data identify a novel presenilin 1-dependent neuroprotective mechanism against excitotoxicity and indicate a pathway by which presenilin 1 familial Alzheimer disease mutants decrease factor-depended neuroprotection against excitotoxicity and ischaemia in the absence of Alzheimer disease neuropathological hallmarks which may form downstream of neuronal damage. These findings have implications for the pathogenic effects of familial Alzheimer disease mutants and therapeutic strategies.This work was supported by National Institutes of Health grants 2RF1AG008200-29; 2R01-NS047229; P50AG05138; and by Grant AARF-17-531426 of the Alzheimer's Association

Donanemab, another anti-Alzheimer's drug with risk and uncertain benefit

Based on “reducing amyloid plaques in the brain”, the U.S. Food and Drug Administration has granted accelerated and full approval for two monoclonal anti-Alzheimer's antibodies, aducanumab and lecanemab, respectively. Approval of a third antibody, donanemab, is pending. Moreover, lecanemab and donanemab are claimed to cause delay in the cognitive decline that characterizes the disease. We believe that these findings are subject to misinterpretation and statistical bias. Donanemab is claimed to cause removal of up to 86 % of cerebral amyloid and 36 % delay in cognitive decline compared to placebo. In reality, these are very small changes on an absolute scale and arguably less than what can be achieved with cholinesterase inhibitor/memantine therapy. Moreover, the “removal” of amyloid, based on the reduced accumulation of amyloid-PET tracer, most likely also reflects therapy-related tissue damage. This would also correlate with the minimal clinical effect, the increased frequency of amyloid-related imaging abnormalities, and the accelerated loss of brain volume in treated compared to placebo patients observed with these antibodies. We recommend halting approvals of anti-AD antibodies until these issues are fully understood to ensure that antibody treatment does not cause more harm than benefit to patients.</p

Расчет, проектирование и монтаж каркаса автостоянки открытого типа

Актуальность работы: в данной выпускной квалификационной работе выполняются расчет и проектирование каркаса автостоянки открытого типа. Целью работы является разработка технологии изготовления каркаса. Целью данного курсового проекта является изучение составных частей изделия, определение марки стали, выбор метода сварки, определение режимов сварки и сварочных материалов, нормализация операций, составление технологического процесса, расчет необходимого количества оборудования и работников.Relevance of work: in this final qualification work, the calculation and design of the open-type carcass frame are performed. The aim of the work is to develop a technology for manufacturing a carcass. The objectives of this course project is to study the component parts of a product, determine the grade of steel, choose a welding method, determine welding modes and welding materials, normalize operations, draw up a process, calculate the required amount of equipment and the number of workers

Magnesium treatment for patients with refractory status epilepticus due to POLG1-mutations

Mutations in the gene encoding of the catalytic subunit of mtDNA polymerase gamma (POLG1) can cause typical Alpers' syndrome. Recently, a new POLG1 mutation phenotype was described, the so-called juvenile-onset Alpers' syndrome. This POLG1 mutation phenotype is characterized by refractory epilepsy with recurrent status epilepticus and episodes of epilepsia partialis continua, which often necessitate admission to the intensive care unit (ICU) and pose an important mortality risk. We describe two previously healthy unrelated teenage girls, who both were admitted with generalized tonic-clonic seizures and visual symptoms leading to a DNA-supported diagnosis of juvenile-onset Alpers' syndrome. Despite combined treatment with anti-epileptic drugs, both patients developed status epilepticus requiring admission to the ICU. Intravenous magnesium as anti-convulsant therapy was initiated, resulting in clinical and neurophysiological improvement and rapid extubation of both patients. Treating status epilepticus in juvenile-onset Alpers' syndrome with magnesium has not been described previously. Given the difficulties encountered while treating epilepsy in patients with this syndrome, magnesium therapy might be considered

Presenilin1 familial Alzheimer disease mutants inactivate EFNB1- and BDNF-dependent neuroprotection against excitotoxicity by affecting neuroprotective complexes of N-methyl-d-aspartate receptor

Excitotoxicity is thought to play key roles in brain neurodegeneration and stroke. Here we show that neuroprotection against excitotoxicity by trophic factors EFNB1 and brain-derived neurotrophic factor (called here factors) requires de novo formation of 'survival complexes' which are factor-stimulated complexes of N-methyl-d-aspartate receptor with factor receptor and presenilin 1. Absence of presenilin 1 reduces the formation of survival complexes and abolishes neuroprotection. EPH receptor B2- and N-methyl-d-aspartate receptor-derived peptides designed to disrupt formation of survival complexes also decrease the factor-stimulated neuroprotection. Strikingly, factor-dependent neuroprotection and levels of the de novo factor-stimulated survival complexes decrease dramatically in neurons expressing presenilin 1 familial Alzheimer disease mutants. Mouse neurons and brains expressing presenilin 1 familial Alzheimer disease mutants contain increased amounts of constitutive presenilin 1-N-methyl-d-aspartate receptor complexes unresponsive to factors. Interestingly, the stability of the familial Alzheimer disease presenilin 1-N-methyl-d-aspartate receptor complexes differs from that of wild type complexes and neurons of mutant-expressing brains are more vulnerable to cerebral ischaemia than neurons of wild type brains. Furthermore, N-methyl-d-aspartate receptor-mediated excitatory post-synaptic currents at CA1 synapses are altered by presenilin 1 familial Alzheimer disease mutants. Importantly, high levels of presenilin 1-N-methyl-d-aspartate receptor complexes are also found in post-mortem brains of Alzheimer disease patients expressing presenilin 1 familial Alzheimer disease mutants. Together, our data identify a novel presenilin 1-dependent neuroprotective mechanism against excitotoxicity and indicate a pathway by which presenilin 1 familial Alzheimer disease mutants decrease factor-depended neuroprotection against excitotoxicity and ischaemia in the absence of Alzheimer disease neuropathological hallmarks which may form downstream of neuronal damage. These findings have implications for the pathogenic effects of familial Alzheimer disease mutants and therapeutic strategies.This work was supported by National Institutes of Health grants 2RF1AG008200-29; 2R01-NS047229; P50AG05138; and by Grant AARF-17-531426 of the Alzheimer’s Association.Peer reviewe