Second Messenger Systems in Alzheimer's Disease: A Quantitative Autoradiographic Study

Quantitative ligand binding autoradiography was used to map key components of second messenger systems in the CNS. [3H]-Forskolin binding to Gs-adenylate cyclase and [3H]-phorbol 12,13 dibutyrate (PDBu) binding to protein kinase C was investigated in human postmortem brain of control patients and patients with Alzheimer's Disease (AD). Disruption of glutamatergic and cholinergic systems may contribute to the pathology of AD. In view of this, alterations in ligand binding sites following selective lesions of glutamatergic and cholinergic pathways in rat brain were used as a framework on which to elucidate possible plastic modifications of second messenger systems in AD. Since the primary lesion in AD occurs within the cortex, ligand binding to second messenger systems was investigated following excitotoxic lesion of the rat cerebral cortex. Second Messenger Ligand Binding in Alzheimer's Disease:In two separate series, [3H]-forskolin binding was investigated in a total of 15 controls and 16 age-matched patients dying with AD in middle frontal and temporal cortices and in the hippocampal formation. AD brains contained numerous neuritic plaques in both cortical areas and the hippocampal region, whilst controls had minimal neuritic plaques. Choline acetyltransferase (ChAT) activity was significantly reduced (>50%) in AD compared to control subjects in both cortex and the hippocampus. [3H]-Forskolin binding was significantly reduced by approximately 50% in all layers of the middle frontal cortex in AD brain compared to controls. There was a positive correlation between [3H]-forskolin binding and ChAT activity in each layer of frontal cortex (correlation coefficient, r = 0.662 - 0.712) when data from control and AD brain were combined. [3H]-Forskolin binding was minimally altered in 1 of the 11 discrete regions examined in the hippocampus in AD brain compared to control. ChAT activity and [3H]-forskolin binding were unrelated in any region of the hippocampus (r = 0.42 - 0.6). In the temporal cortex and the molecular layer of the dentate gyrus, there was evidence that [3 H]-forskolin binding was lower in AD patients compared to control subjects. Whether these changes achieved the probability level of 5% was a reflection of group size, variability of measurements, and the errors of sampling heterogeneous populations. There was no association between the number of neuritic plaques and [3H]-forskolin binding in any brain region examined. The effect of 5'guanylimidodiphosphate (Gpp(NH)p) on [3H]-forskolin binding was examined in adjacent sections from the same group of control and AD patients. In control brain, basal levels of [3H]-forskolin binding were significantly increased in layers I-III of middle frontal cortex (28%) and middle temporal cortex (30%) in the presence of Gpp(NH)p. In AD brain, the ability of Gpp(NH)p to enhance [3H]-forskolin binding from basal levels in cortical layers (I-III) was conserved. Gpp(NH)p had no effect on the level of [3H]-forskolin binding within each region of the hippocampus in the control or AD group. In a separate study, both quantitative autoradiography and homogenate binding to particulate and cytosolic fractions were employed to investigate [3H]-PDBu binding in middle frontal and temporal cortices, and the hippocampal region of nine control and nine AD subjects. All AD brains exhibited extensive signs of the pathology classically associated with the disease, namely numerous neuritic plaques and a profound reduction in ChAT activity ( 60%) in both cortical areas and the hippocampus. Quantitative autoradiographic analysis of [3H]-PDBu binding showed there was no significant difference between control and AD sections in all areas examined within the middle frontal and temporal cortices and hippocampal formation. In adjacent sections to those used for [3H]-PDBu autoradiography, [3H]-forskolin binding was markedly reduced in all layers of middle frontal and temporal cortex (at least 30%) and in the molecular layer of the dentate gyrus (38%) in AD when compared with control subjects. In a parallel study, [3H]-PDBu binding to homogenate preparations of control and AD brain confirmed that there was no significant difference in [3H]-PDBu binding in either the particulate or cytosolic fraction. (Abstract shortened by ProQuest.)

Multimetallic lithium complexes derived from the acids Ph₂C(X)CO₂H (X = OH, NH₂) : synthesis, structure and ring opening polymerization of lactides and lactones

Reaction of LiOR (R=t-Bu, Ph) with the acids 2,2/-Ph₂C(X)(CO₂H), X=OH (benzH), NH₂ (dpgH) was investigated. For benzH, one equivalent LiOt-Bu in THF afforded [Li(benz)]2⋅2THF (1⋅2THF), which adopts a 1D chain structure. If acetonitrile is used (mild conditions), another polymorph of 1 is isolated; LiOPh also led to 1. Robust work-up afforded [Li₇(benz)₇(MeCN)] 2MeCN THF (2⋅2MeCN⋅THF). Use of LiOt-Bu (2 equivalents) led to {Li₈(Ot-Bu)₂[(benz)](OCPh₂CO₂CPh₂CO2t-Bu)₂(THF)₄} (3), the core of which comprises two open cubes linked by benz ligands. For dpgH, two equivalents of LiOt-Bu in THF afforded [Li6(Ot-Bu)₂(dpg)₂(THF)₂] (4), which contains an Li₂Ov 6-step ladder. Similar reaction of LiOPh afforded [Li₈(PhO)₄(dpg)₄(MeCN)₄] (5). Complexes 1–5 were screened for their potential as catalysts for ring opening polymerization (ROP) of ϵ-caprolactone (ϵ-CL), rac-lactide (rac-LA) and δ-valerolactone (δ-VL). For ROP of ϵ-CL, conversions > 70 % were achievable at 110 °C with good control. For rac-LA and δ-VL, temperatures of at least 110 °C over 12 h were necessary for activity (conversions > 60 %). Systems employing 2 were inactiv

Restoration of oligodendrocyte pools in a mouse model of chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion, a sustained modest reduction in cerebral blood flow, is associated with damage to myelinated axons and cognitive decline with ageing. Oligodendrocytes (the myelin producing cells) and their precursor cells (OPCs) may be vulnerable to the effects of hypoperfusion and in some forms of injury OPCs have the potential to respond and repair damage by increased proliferation and differentiation. Using a mouse model of cerebral hypoperfusion we have characterised the acute and long term responses of oligodendrocytes and OPCs to hypoperfusion in the corpus callosum. Following 3 days of hypoperfusion, numbers of OPCs and mature oligodendrocytes were significantly decreased compared to controls. However following 1 month of hypoperfusion, the OPC pool was restored and increased numbers of oligodendrocytes were observed. Assessment of proliferation using PCNA showed no significant differences between groups at either time point but showed reduced numbers of proliferating oligodendroglia at 3 days consistent with the loss of OPCs. Cumulative BrdU labelling experiments revealed higher numbers of proliferating cells in hypoperfused animals compared to controls and showed a proportion of these newly generated cells had differentiated into oligodendrocytes in a subset of animals. Expression of GPR17, a receptor important for the regulation of OPC differentiation following injury, was decreased following short term hypoperfusion. Despite changes to oligodendrocyte numbers there were no changes to the myelin sheath as revealed by ultrastructural assessment and fluoromyelin however axon-glial integrity was disrupted after both 3 days and 1 month hypoperfusion. Taken together, our results demonstrate the initial vulnerability of oligodendroglial pools to modest reductions in blood flow and highlight the regenerative capacity of these cells

Why do people choose nephrology? Identifying positive motivators to aid recruitment and retention

Increasing concerns about recruitment and retention of junior doctors have led to renewed interest in how and when trainees choose their specialties. To our knowledge, no study has yet reported what attracts UK applicants to nephrology nor how clinicians develop vocational interests or make occupational choices. With this in mind, we sought to explore the motivation behind current nephrologist's career choices in the UK. We interviewed 11 nephrologists using a semi-structured face-to-face approach and used interpretative phenomenological analysis to conduct and analyse the interviews. We found role models were pivotal in encouraging specialization in nephrology, particularly those encountered in early postgraduate training. The diversity, diagnostic challenge and cross-specialty knowledge was highlighted as well as the ability to 'make a difference to patients' lives'. Nephrologists enjoyed the challenge of managing very sick, acutely unwell patients as well as the holistic continuity of long-term care offered to dialysis patients and their families. Academic and procedural components were attractive motivators to the specialty and the flexibility to have multiple interests was noted, with many nephrologists having 'portfolio' careers. Based on these results, we suggest strategies the specialty can use to aid policy decision making, promote recruitment and improve educational experiences within current training programmes

AcmA of Lactococcus lactis is an N-acetylglucosaminidase with an optimal number of LysM domains for proper functioning

AcmA, the major autolysin of Lactococcus lactis MG1363 is a modular protein consisting of an N-terminal active site domain and a C-terminal peptidoglycan-binding domain. The active site domain is homologous to that of muramidase-2 of Enterococcus hirae, however, RP-HPLC analysis of muropeptides released from Bacillus subtilis peptidoglycan, after digestion with AcmA, shows that AcmA is an N-acetylglucosaminidase. In the C-terminus of AcmA three highly similar repeated regions of 45 amino acid residues are present, which are separated by short nonhomologous sequences. The repeats of AcmA, which belong to the lysine motif (LysM) domain family, were consecutively deleted, removed, or, alternatively, one additional repeat was added, without destroying the cell wall-hydrolyzing activity of the enzyme in vitro, although AcmA activity was reduced in all cases. In vivo, proteins containing no or only one repeat did not give rise to autolysis of lactococcal cells, whereas separation of the producer cells from the chains was incomplete. Exogenously added AcmA deletion derivatives carrying two repeats or four repeats bound to lactococcal cells, whereas the derivative with no or one repeat did not. In conclusion, these results show that AcmA needs three LysM domains for optimal peptidoglycan binding and biological functioning

Regio-selective substitution at the 1,3- and 6,8-positions of pyrene for the construction of small dipolar molecules

© 2015 American Chemical Society. This article presents a novel asymmetrical functionalization strategy for the construction of dipolar molecules via efficient regioselective functionalization along the Z-axis of pyrene at both the 1,3- and 6,8-positions. Three asymmetrical ly substituted 1,3-diphenyl-6,8-R-disubsituted pyrenes were fully characterized by X-ray crystallography, photophysical properties, electrochemistry, and density functional theory calculations

Data assmilation tests using NISE10 Storm Surge Model

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Toxin-mediated competition in weakly motile bacteria

Many bacterial species produce toxins that inhibit their competitors. We model this phenomenon by extending classic two-species Lotka-Volterra competition in one spatial dimension to incorporate toxin production by one species. Considering solutions comprising two adjacent single-species colonies, we show how the toxin inhibits the susceptible species near the interface between the two colonies. Moreover, a sufficiently effective toxin inhibits the susceptible species to such a degree that an `inhibition zone' is formed separating the two colonies. In the special case of truly non-motile bacteria, i.e. with zero bacterial diffusivity, we derive analytical expressions describing the bacterial distributions and size of the inhibition zone. In the more general case of weakly motile bacteria, i.e. small bacterial diffusivity, these two-colony solutions become travelling waves. We employ numerical methods to show that the wavespeed is dependent upon both interspecific competition and toxin strength; precisely which colony expands at the expense of the other depends upon the choice of parameter values. In particular, a sufficiently effective toxin allows the producer to expand at the expense of the susceptible, with a wavespeed magnitude that is bounded above as the toxin strength increases. This asymptotic wavespeed is independent of interspecific competition and due to the formation of the inhibition zone; when the colonies are thus separated, there is no longer direct competition between the two species and the producer can invade effectively unimpeded by its competitor. We note that the minimum toxin strength required to produce an inhibition zone increases rapidly with increasing bacterial diffusivity, suggesting that even moderately motile bacteria must produce very strong toxins if they are to benefit in this way

Перевірка суб’єктів господарювання державного сектора економіки: ревізія чи аудит?

The house sparrow (Passer domesticus) is an important model species in ecology and evolution. However, until recently, genomic resources for molecular ecological projects have been lacking in this species. Here, we present transcriptome sequencing data (RNA-Seq) from three different house sparrow tissues (spleen, blood and bursa). These tissues were specifically chosen to obtain a diverse representation of expressed genes and to maximize the yield of immune-related gene functions. After de novo assembly, 15250 contigs were identified, representing sequence data from a total of 8756 known avian genes (as inferred from the closely related zebra finch). The transcriptome assembly contain sequence data from nine manually annotated MHC genes, including an almost complete MHC class I coding sequence. There were 407, 303 and 68 genes overexpressed in spleen, blood and bursa, respectively. Gene ontology terms related to ribosomal function were associated with overexpression in spleen and oxygen transport functions with overexpression in blood. In addition to the transcript sequences, we provide 327 gene-linked microsatellites (SSRs) with sufficient flanking sequences for primer design, and 3177 single-nucleotide polymorphisms (SNPs) within genes, that can be used in follow-up molecular ecology studies of this ecological well-studied species