Confocal Laser Scanning Microscopic Studies on Alveolar Bone Remodeling with Orthodontic Tooth Movement and Retention

Alveolar bone reconstruction in growing dog during the retention period following orthodontic tooth movement was studied. Three beagle dogs (8-10 kg body weight, about one-year-old) were used and two of the animals were subjected to histological observation. The upper 2nd and lower 3rd premolars on both sides were extracted prior to the orthodontic treatments. After a healing period of one month, the upper 3rd premolar and the lower 4th premolar on the right side were moved mesially with a conventional orthodontic force for 8 weeks, and then retained in their new position for 4 weeks. The contralateral corresponding premolars were used as control. The alveolar bone was double-labeled with tetracycline (TC) during the movement and calcein (Cal) during the retention period. Alveolar bone structure and labeling patterns were examined by contact microradiography, conventional fluorescence microscopy, and confocal laser scanning microscopy (CLSM). Optimizing the separation of TC and Cal labelings in the alveolar bone was attained by the simultaneous use of ultraviolet (364 nm) and argon (488 nm) laser sources for excitation of TC and Cal, respectively. Cal labeling, indicative of new bone deposition showed two distinct patterns: lamination at the periodontal surface and rings circumscribing the vascular canal. The cementum surface also exhibited active deposition during the experimental period. Bone formation was affected by slight changes in magnitude and direction of orthodontic or occlusal forces. CLSM is valuable in deciphering the process of alveolar bone remodeling

Ku70 alleviates neurodegeneration in drosophila models of Huntington's disease

DNA damage accumulates in genome DNA during the long life of neurons, thus DNA damage repair is indispensable to keep normal functions of neurons. We previously reported that Ku70, a critical molecule for DNA double strand break (DSB) repair, is involved in the pathology of Huntington's disease (HD). Mutant huntingtin (Htt) impaired Ku70 function via direct interaction, and Ku70 supplementation recovered phenotypes of a mouse HD model. In this study, we generate multiple Drosophila HD models that express mutant huntingtin (Htt) in eye or motor neuron by different drivers and show various phenotypes. In such fly models, Ku70 co-expression recovers lifespan, locomotive activity and eye degeneration. In contrast, Ku70 reduction by heterozygous null mutation or siRNA-mediated knock down accelerates lifespan shortening and locomotion disability. These results collectively support that Ku70 is a critical mediator of the HD pathology and a candidate therapeutic target in HD

Calpain-mediated degradation of p35 to p25 in postmortem human and rat brains

AbstractTau in Alzheimer neurofibrillary tangles has been shown to be hyperphosphorylated and CDK5, GSK3, MAP kinase and SAP kinases are the candidate kinases for the phosphorylation of tau. Recently, it was reported that the conversion of p35, the activator of CDK5, to p25 was upregulated in Alzheimer’s disease (AD) brains, and that p35 is cleaved to yield p25 by calpain. Here we show that p35 is rapidly cleaved to p25 in rat and human brains within a short postmortem delay and that the conversion of p35 to p25 is partially dependent on calpain activity. Immunoblot analysis of brains prepared from patients with AD or age-matched control individuals with a short postmortem delay revealed no specific increase in the levels of p25 in AD brains, whereas the levels of active form of calpain were increased in AD brains compared to the those in controls. These observations suggest that the conversion of p35 to p25 is a postmortem degradation event and may not be upregulated in AD brains

Similar promotion of Aβ(1-42 )fibrillogenesis by native apolipoprotein E ε3 and ε4 isoforms

The apolipoprotein E ε4 allele contributes to the genetic susceptibility underlying a large proportion (~40–60%) of typical, sporadic Alzheimer disease. Apolipoprotein E deficient mice made transgenic for human apolipoprotein E ε4 accumulate excess cerebral amyloid when compared to similarly prepared mice expressing human apolipoprotein E ε3. Therefore, it is important to search for relevant interactions(s) between apolipoprotein E ε4 and Aβ in order to clarify the biological role for apolipoprotein E ε4 in Alzheimer disease. Using a thioflavine T (ThT)-based assay, we have investigated the effects of native human apolipoprotein E isoforms on the kinetics of Aβ fibrillogenesis. No obvious profibrillogenic activity was detected in Aβ(1-40)-based assays of any native apolipoprotein E isoform. However, when ThT assays were repeated using Aβ(1-42), modest, but statistically significant, profibrillogenic activity was detected in both apolipoprotein E ε3- and apolipoprotein E ε4-containing media and was similar in magnitude for the two isoforms. These data demonstrate that native apolipoprotein E possesses "pathological chaperone"-type activity for Aβ: in other words, the data indicate that a chaperone-like misfolding reaction can occur between native apolipoprotein E and Aβ. However, the equipotent activities of the apolipoprotein E ε3 and ε4 isoforms suggests the possibility that either extended co-incubation of apolipoprotein E and Aβ, or, perhaps, the inclusion in the reaction of other fibrillogenesis-modulation co-factors (such as metal ions, or inflammatory mediators such as reactive oxygen species, α(2)-macroglobulin, apolipoprotein J, etc.) may be required for modeling in vitro the apolipoprotein E-isoform-specific-regulation of extracellular Aβ accumulation that occurs in vivo. Alternatively, other events, such as differential apolipoprotein E-isoform-mediated clearance of Aβ or of apolipoprotein E/Aβ complexes may underlie apolipoprotein E-isoform-dependent Aβ accumulation

The Amyloid-beta Pathway in Alzheimer's Disease

Breakthroughs in molecular medicine have positioned the amyloid-β (Aβ) pathway at the center of Alzheimer’s disease (AD) pathophysiology. While the detailed molecular mechanisms of the pathway and the spatial-temporal dynamics leading to synaptic failure, neurodegeneration, and clinical onset are still under intense investigation, the established biochemical alterations of the Aβ cycle remain the core biological hallmark of AD and are promising targets for the development of disease-modifying therapies. Here, we systematically review and update the vast state-of-the-art literature of Aβ science with evidence from basic research studies to human genetic and multi-modal biomarker investigations, which supports a crucial role of Aβ pathway dyshomeostasis in AD pathophysiological dynamics. We discuss the evidence highlighting a differentiated interaction of distinct Aβ species with other AD-related biological mechanisms, such as tau-mediated, neuroimmune and inflammatory changes, as well as a neurochemical imbalance. Through the lens of the latest development of multimodal in vivo biomarkers of AD, this cross-disciplinary review examines the compelling hypothesis- and data-driven rationale for Aβ-targeting therapeutic strategies in development for the early treatment of AD

Correlation effects during liquid infiltration into hydrophobic nanoporous mediums

Correlation effects arising during liquid infiltration into hydrophobic porous medium are considered. On the basis of these effects a mechanism of energy absorption at filling porous medium by nonwetting liquid is suggested. In accordance with this mechanism, the absorption of mechanical energy is a result expenditure of energy for the formation of menisci in the pores on the shell of the infinite cluster and expenditure of energy for the formation of liquid-porous medium interface in the pores belonging to the infinite cluster of filled pores. It was found that in dependences on the porosity and, consequently, in dependences on the number of filled pores neighbors, the thermal effect of filling can be either positive or negative and the cycle of infiltration-defiltration can be closed with full outflow of liquid. It can occur under certain relation between percolation properties of porous medium and the energy characteristics of the liquid-porous medium interface and the liquid-gas interface. It is shown that a consecutive account of these correlation effects and percolation properties of the pores space during infiltration allow to describe all experimental data under discussion

Pyroglutamate Abeta pathology in APP/PS1KI mice, sporadic and familial Alzheimer’s disease cases

The presence of AβpE3 (N-terminal truncated Aβ starting with pyroglutamate) in Alzheimer’s disease (AD) has received considerable attention since the discovery that this peptide represents a dominant fraction of Aβ peptides in senile plaques of AD brains. This was later confirmed by other reports investigating AD and Down’s syndrome postmortem brain tissue. Importantly, AβpE3 has a higher aggregation propensity, and stability, and shows an increased toxicity compared to full-length Aβ. We have recently shown that intraneuronal accumulation of AβpE3 peptides induces a severe neuron loss and an associated neurological phenotype in the TBA2 mouse model for AD. Given the increasing interest in AβpE3, we have generated two novel monoclonal antibodies which were characterized as highly specific for AβpE3 peptides and herein used to analyze plaque deposition in APP/PS1KI mice, an AD model with severe neuron loss and learning deficits. This was compared with the plaque pattern present in brain tissue from sporadic and familial AD cases. Abundant plaques positive for AβpE3 were present in patients with sporadic AD and familial AD including those carrying mutations in APP (arctic and Swedish) and PS1. Interestingly, in APP/PS1KI mice we observed a continuous increase in AβpE3 plaque load with increasing age, while the density for Aβ1-x plaques declined with aging. We therefore assume that, in particular, the peptides starting with position 1 of Aβ are N-truncated as disease progresses, and that, AβpE3 positive plaques are resistant to age-dependent degradation likely due to their high stability and propensity to aggregate

Anti-Aβ Drug Screening Platform Using Human iPS Cell-Derived Neurons for the Treatment of Alzheimer's Disease

Background:Alzheimer's disease (AD) is a neurodegenerative disorder that causes progressive memory and cognitive decline during middle to late adult life. The AD brain is characterized by deposition of amyloid β peptide (Aβ), which is produced from amyloid precursor protein by β- and γ-secretase (presenilin complex)-mediated sequential cleavage. Induced pluripotent stem (iPS) cells potentially provide an opportunity to generate a human cell-based model of AD that would be crucial for drug discovery as well as for investigating mechanisms of the disease. Methodology/Principal Findings:We differentiated human iPS (hiPS) cells into neuronal cells expressing the forebrain marker, Foxg1, and the neocortical markers, Cux1, Satb2, Ctip2, and Tbr1. The iPS cell-derived neuronal cells also expressed amyloid precursor protein, β-secretase, and γ-secretase components, and were capable of secreting Aβ into the conditioned media. Aβ production was inhibited by β-secretase inhibitor, γ-secretase inhibitor (GSI), and an NSAID; however, there were different susceptibilities to all three drugs between early and late differentiation stages. At the early differentiation stage, GSI treatment caused a fast increase at lower dose (Aβ surge) and drastic decline of Aβ production. Conclusions/Significance:These results indicate that the hiPS cell-derived neuronal cells express functional β- and γ-secretases involved in Aβ production; however, anti-Aβ drug screening using these hiPS cell-derived neuronal cells requires sufficient neuronal differentiation

Distinct glutaminyl cyclase expression in Edinger–Westphal nucleus, locus coeruleus and nucleus basalis Meynert contributes to pGlu-Aβ pathology in Alzheimer’s disease

Glutaminyl cyclase (QC) was discovered recently as the enzyme catalyzing the pyroglutamate (pGlu or pE) modification of N-terminally truncated Alzheimer’s disease (AD) Aβ peptides in vivo. This modification confers resistance to proteolysis, rapid aggregation and neurotoxicity and can be prevented by QC inhibitors in vitro and in vivo, as shown in transgenic animal models. However, in mouse brain QC is only expressed by a relatively low proportion of neurons in most neocortical and hippocampal subregions. Here, we demonstrate that QC is highly abundant in subcortical brain nuclei severely affected in AD. In particular, QC is expressed by virtually all urocortin-1-positive, but not by cholinergic neurons of the Edinger–Westphal nucleus, by noradrenergic locus coeruleus and by cholinergic nucleus basalis magnocellularis neurons in mouse brain. In human brain, QC is expressed by both, urocortin-1 and cholinergic Edinger–Westphal neurons and by locus coeruleus and nucleus basalis Meynert neurons. In brains from AD patients, these neuronal populations displayed intraneuronal pE-Aβ immunoreactivity and morphological signs of degeneration as well as extracellular pE-Aβ deposits. Adjacent AD brain structures lacking QC expression and brains from control subjects were devoid of such aggregates. This is the first demonstration of QC expression and pE-Aβ formation in subcortical brain regions affected in AD. Our results may explain the high vulnerability of defined subcortical neuronal populations and their central target areas in AD as a consequence of QC expression and pE-Aβ formation