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Two major questions in the field of Alzheimer-type dementia remain elusive. One is the native function of amyloid-β (Aβ) peptides and the other is an early deficit in the central cholinergic network. Nevertheless, recent evidence suggests that Aβ peptides are involved in the regulation of acetylcholine (ACh) homeostasis either by allosteric activation of ACh-degrading cholinesterases or by inhibiting the high-affinity choline uptake transporter. In the current study, we report that Aβ peptides, in particular Aβ42, allosterically enhances the catalytic rate of the core-cholinergic enzyme choline acetyltransferase (ChAT), responsible for biosynthesis of ACh. Detailed in vitro enzyme kinetic analysis indicated that both soluble Aβ40 and Aβ42 enhanced the catalytic efficiency of ChAT by ∼21% and 26% at physiological concentration ranges found in human cerebrospinal fluid (CSF). Further analyses indicated that activation of ChAT by Aβ was highly specific. Intriguingly, Aβ42 exhibited an EC50 of activation potency at 10-fold lower concentrations compared to Aβ40. The activation was persistent even in the presence of a physiological Aβ 40/42 mixture ratio, expected in human CSF. In conclusion, we report for the first time that Aβ42 peptide acts as allosteric enhancers of ACh-biosynthesizing enzyme ChAT. Together with two previous observations, this points to a complex molecular cross-talk between Aβ and the enzymatic machinery involved in maintaining cellular, synaptic and extra-synaptic ACh homeostasis, warranting further investigation. [ABSTRACT FROM AUTHOR]

Objective To investigate pregnancy outcome for fetuses with nuchal translucency (NT) ≥3.5 mm but normal karyotype in the Stockholm (Sweden) area. Methods A retrospective population-based cohort study. From 2006 to 2012, fetal NT was measured in 55123 singleton pregnancies. There were 341 pregnancies with NT thickness ≥3.5 mm; 139 had a normal karyotype, 164 had an abnormal karyotype and 38 were removed from the study. Pregnancy outcome was defined as adverse (termination of pregnancy [TOP], miscarriage [MC], intrauterine fetal death [IUFD], or delivery of a child with structural defects or genetic disorders), or favourable (delivery of a child without any structural defects or genetic disorders diagnosed before discharge). Results Of the 139 high NT pregnancies with normal karyotype, 110 (79.2%) resulted in live births, one (0.7%) IUFD, 23 (16.5%) TOP and five (3.6%) MC. The risk of an adverse pregnancy outcome increased with increasing NT. Structural fetal defects were found in 28 (19.5%) of pregnancies undergoing second trimester ultrasound screening, of which seven resulted in live births and 21 were terminated. The most common structural defect was cardiac defects. Conclusions Adverse pregnancy outcome increased with increasing NT, even with normal karyotype, however, the prognosis is good if the second trimester ultrasound screening is normal. [ABSTRACT FROM AUTHOR]

Background: Although genetic and biochemical studies have suggested a cardinal role for β-amyloid (Aβ) in Alzheimer's disease, the underlying mechanism(s) of how Aβ induces neurodegeneration is still unclear. Our objective was to investigate the consequences of Aβ, especially on tau phosphorylation at specific epitopes important for Alzheimer's disease., Methods: We used cortices from Tg2576 mice at 7 days to 15 months of age., Results: MALDI-TOF MS revealed an age-dependent shift in the Aβ isoform pattern. Young animals displayed high cortical levels of the shorter Aβ isoforms (Aβ1-16 and Aβ1-17) compared to 15-month-old Tg2576 mice which mainly expressed Aβ1-40 and Aβ1-42. The Aβ1-42 showed an age-dependent increase, whereas total Aβ1-40 levels remained constant. The highest levels of TBS-soluble Aβ oligomers were found at 90 days of age. Brain Aβ build-up did not affect the phosphorylation of tau at the epitopes investigated., Conclusions: This study provides new information about age-dependent Aβ isoforms and oligomers as well as their effect on site-specific tau phosphorylation in this transgenic mouse model. Our observations suggest that the different human Aβ isoforms do not directly cause increased tau phosphorylation and that the cognitive deficits seen in this mouse model are only related to the Aβ overexpression., (Copyright © 2011 S. Karger AG, Basel.)

Background: Several studies implicate acetylcholinesterase (AChE) in the pathogenesis of Alzheimer's disease (AD), raising the question of whether inhibitors of AChE also might act in a disease-modifying manner. Huprine X (HX), a reversible AChE inhibitor hybrid of tacrine and huperzine A, has shown to affect the amyloidogenic process in vitro. In this study, the aim was to investigate whether HX could affect the AD-related neuropathology in vivo in two mouse models., Methods: Tg2576 (K670M/N671L) (APPswe) and 3xTg-AD (K670M/N671L, PS1M146V, tauP301L) mice were treated with HX (0.12 μmol/kg, i.p., 21 days) or saline at 6-7 months. Human β-amyloid (Aβ) was measured by ELISA, synaptophysin by Western blot and α7 neuronal nicotinic acetylcholine receptors (nAChRs) were analyzed by [(125)I]α-bungarotoxin autoradiography., Results: Treatment with HX reduced insoluble Aβ1-40 (about 40%) in the hippocampus of 3xTg-AD mice, while showing no effect in APPswe mice. Additionally, HX markedly increased cortical synaptophysin levels (about 140%) and decreased (about 30%) the levels of α7 nAChRs in the caudate nucleus of 3xTg-AD mice, while increasing (about 10%) hippocampal α7 nAChRs in APPswe mice., Conclusion: The two mouse models react differently to HX treatment, possibly due to their differences in brain neuropathology. The modulation of Aβ and synaptophysin by HX in 3xTg-AD mice might be due to its suggested interaction with the peripheral anionic site on AChE, and/or via cholinergic mechanisms involving activation of cholinergic receptors. Our results provide further evidence that drugs targeting AChE affect some of the fundamental processes that contribute to neurodegeneration, but whether HX might act in a disease-modifying manner in AD patients remains to be proven., (Copyright © 2010 S. Karger AG, Basel.)