The cholinergic hypothesis of neuropsychiatric symptoms in Alzheimer's disease

A variety of neuropsychiatric symptoms occur in Alzheimer's disease (AD) including agitation, psychosis, depression, apathy, disinhibition, anxiety, purposeless behavior, and disorders of sleep and appetite. Neuropsychiatric symptoms have been related to cholinergic deficiency and improve after treatment with cholinomimetic agents. Cholinergic drugs are unique among psychotropic agents in exerting disease-specific and broad-spectrum effects. These observations provide the basis for the cholinergic hypothesis of the neuropsychiatric symptoms of AD, suggesting that the cholinergic deficit of AD contributes to the neuropsychiatric symptoms of AD and that cholinomimetic therapy ameliorates the behavioral disturbances accompanying AD.

Microbial interactions in building of communities

Establishment of a community is considered to be essential for microbial growth and survival in the human oral cavity. Biofilm communities have increased resilience to physical forces, antimicrobial agents and nutritional variations. Specific cell-to-cell adherence processes, mediated by adhesin-receptor pairings on respective microbial surfaces, are able to direct community development. These interactions co-localize species in mutually beneficial relationships, such as streptococci, veillonellae, Porphyromonas gingivalis and Candida albicans. In transition from the planktonic mode of growth to a biofilm community, microorganisms undergo major transcriptional and proteomic changes. These occur in response to sensing of diffusible signals, such as autoinducer molecules, and to contact with host tissues or other microbial cells. Underpinning many of these processes are intracellular phosphorylation events that regulate a large number of microbial interactions relevant to community formation and development.

Intra-specific heterogeneity of the rDNA internal transcribed spacer in the Simulium damnosum (Diptera: Simuliidae) complex

The internal transcribed spacer (ITS) of the rRNA gene cluster has been used as a model for the study of the action of concerted evolution and molecular drive on repeated sequence families. In contrast to this general finding, preliminary DNA sequence analysis of cloned representatives of the ITS from the West African black fly species complex Simulium damnosum s.1. demonstrated extensive intra-individual and intra-specific polymorphisms. Variability in the ITS was primarily confined to the ITS1 domain. The degree and type of intra-individual and intra-specific variability within the ITS was further characterized using gel electrophoresis, DNA hybridization, and heteroduplex analysis of the PCR products generated from the ITS1 domain. ITS1 copies from individual S. damnosum s.1. differed in length and sequence composition. These results, when taken together, demonstrate that a large degree of intra-individual and intra-specific heterogeneity exists in the ITS of S. damnosum s.1. The intra-individual heterogeneity was greater in the savanna-dwelling than forest-dwelling sibling species of S. damnosum s.1. This heterogeneity may be due in part to inter-breeding among sympatric sibling species, coupled with disturbance of S. damnosum s.1. populations resulting from intensive vector control efforts.

The 2021 Magnonics Roadmap

Magnonics is a budding research field in nanomagnetism and nanoscience that addresses the use of spin waves (magnons) to transmit, store, and process information. The rapid advancements of this field during last one decade in terms of upsurge in research papers, review articles, citations, proposals of devices as well as introduction of new sub-topics prompted us to present the first roadmap on magnonics. This is a collection of 22 sections written by leading experts in this field who review and discuss the current status besides presenting their vision of future perspectives. Today, the principal challenges in applied magnonics are the excitation of sub-100 nm wavelength magnons, their manipulation on the nanoscale and the creation of sub-micrometre devices using low-Gilbert damping magnetic materials and its interconnections to standard electronics. To this end, magnonics offers lower energy consumption, easier integrability and compatibility with CMOS structure, reprogrammability, shorter wavelength, smaller device features, anisotropic properties, negative group velocity, non-reciprocity and efficient tunability by various external stimuli to name a few. Hence, despite being a young research field, magnonics has come a long way since its early inception. This roadmap asserts a milestone for future emerging research directions in magnonics, and hopefully, it will inspire a series of exciting new articles on the same topic in the coming years.

Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality

The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 microGy/frame (cine) and 5 and 95 mGy min(-1) (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality.

Patient dose in interventional radiology: a European survey

Patient doses for a few common fluoroscopy-guided procedures in interventional radiology (IR) (excluding cardiology) were collected from a few radiological departments in 13 European countries. The major aim was to evaluate patient doses for the basis of the reference levels. In total, data for 20 procedures for about 1300 patients were collected. There were many-fold variations in the number of IR equipment and procedures per population, in the entrance dose rates, and in the patient dose data (total dose area product or DAP, fluoroscopy time and number of frames). There was no clear correlation between the total DAP and entrance dose rate, or between the total DAP and fluoroscopy time, indicating that a number of parameters affect the differences. Because of the limited number of patients, preliminary reference levels were proposed only for a few procedures. There is a need to improve the optimisation of IR procedures and their definitions and grouping, in order to account for their different complexities.

Detection of Onchocerca volvulus infection by O-150 polymerase chain reaction analysis of skin scratches

The standard assay for onchocerciasis diagnosis is microscopic detection of parasites in skin snips. Skin snipping is painful and may potentially transmit bloodborne infections. Thus, an alternative method for the diagnosis of onchocerciasis that does not require skin snipping is needed. A polymerase chain reaction (PCR)-based assay was shown to detect the presence of parasite DNA in superficial skin scrapings. Detection of parasite DNA in both skin snips and skin scratches was found to be more sensitive for detecting low-density infections than was microscopic examination of skin snips. The skin scratch PCR assay is minimally invasive and painless and does not present the risk of transmitting bloodborne infections. These properties make the skin scratch an attractive alternative to the skin snip for detecting O. volvulus infection.

Gender-related cognitive deficits in Alzheimer's disease

Recent studies have identified cognitive deficits in semantic memory and verbal language abilities among women with Alzheimer's disease (AD). Few studies to date have explored gender differences in episodic memory function in AD. The present study compared the performance of men and women diagnosed with AD on a battery of neuropsychological measures. Results indicated the presence of gender-related cognitive deficits on tasks of confrontation naming, expressive word knowledge, and both episodic and semantic memory for women with AD, relative to findings in men.

Criteria for the selection of larvicides by the Onchocerciasis Control Programme in west Africa

One of the weekly decisions the Onchocerciasis Control Programme has to make, in its operations in 11 west African countries, is the selection of one insecticide out of the six used that is most appropriate to the river stretches to be treated. This decision depends on several criteria, linked not only to the compounds themselves but also the hydrological conditions and blackfly populations involved. Given the great number of breeding sites (gites) to be treated, in 23,000 km of rivers at the height of the rainy season, this paper identifies the parameters needed to facilitate the choice of insecticide and to optimize the larviciding in terms of cost effectiveness, management of resistance and minimizing the environmental impact.

SQUID-based detection of ultra-low-field multinuclear NMR of substances hyperpolarized using signal amplification by reversible exchange

Ultra-low-field (ULF) nuclear magnetic resonance (NMR) is a promising spectroscopy method allowing for, e.g., the simultaneous detection of multiple nuclei. To overcome the low signal-to-noise ratio that usually hampers a wider application, we present here an alternative approach to ULF NMR, which makes use of the hyperpolarizing technique signal amplification by reversible exchange (SABRE). In contrast to standard parahydrogen hyperpolarization, SABRE can continuously hyperpolarize 1 H as well as other MR-active nuclei. For simultaneous measurements of 1 H and 19 F under SABRE conditions a superconducting quantum interference device (SQUID)-based NMR detection unit was adapted. We successfully hyperpolarized fluorinated pyridine derivatives with an up to 2000-fold signal enhancement in 19 F. The detected signals may be explained by two alternative reaction mechanisms. SABRE combined with simultaneous SQUID-based broadband multinuclear detection may enable the quantitative analysis of multinuclear processes.

Sibling species distributions of the Simulium damnosum complex in the west African Onchocerciasis Control Programme area during the decade 1984-93, following intensive larviciding since 1974

During the decade from 1984 to 1993, nine species of the Simulium damnosum complex of blackflies (Diptera: Simuliidae) were identified from the area covered by the Onchocerciasis Control Programme. These were S. damnosum s.s., S. dieguerense, S. konkourense, S. leonense, S. sanctipauli, S. sirbanum, S. soubrense, S. squamosum, and S. yahense. Some of these species were found to consist of two chromosomal variant populations. These were S. konkourense 'Konkouré' and 'Menankaya' forms, S. sanctipauli sensu stricto and 'Djodji' form, S. soubrense 'Chute Milo' and 'Beffa' forms. The distribution of these twelve cytological taxa was assessed in relation to the two main vegetation zones of West Africa (forest and savanna), topography, river size and other factors. The range of each species was influenced by seasonal climatic changes in wind movement and river water level. The most widely distributed species were S. sirbanum and S. damnosum s.s., associated with savanna areas, recorded from all river basins. Simulium dieguerense was restricted mainly to Western Mali on the Rivers Bafing and Bakoye in the Senegal River basin. Simulium squamosum was identified from rivers draining mountainous areas in both the forest and savanna zones. Simulium yahense was found in small permanent rivers along a wide forested band parallel to the coast and was absent from the plains of Togo and Benin. Members of the S. sanctipauli subcomplex had restricted distributions except for S. sanctipauli s.s., which was widespread in large rivers of the forest zone from Sierra Leone to the Volta Lake in Ghana. Simulium soubrense 'Beffa' form occurred in Togo and Benin, S. soubrense 'Chutes Milo' form in Guinea, both 'Konkouré' and 'Menankaya' forms of S. konkourense occurred predominantly in Guinea and S. leonense in Sierra Leone. The relevance of the distribution maps and the importance of the data bank to vector control larvicidal operations are discussed.

Vector-parasite transmission complexes for onchocerciasis in West Africa

BACKGROUND

In West Africa, there are two strains of the filarial parasite Onchocerca volvulus, which differ in their ability to induce ocular disease. Transmission studies have suggested that six sibling species of the parasite vector, the black fly Simulium damnosum sensu lato, allow development of the two strains of O volvulus with varying efficiency. We aimed to test the hypothesis of parasite-vector complexes, whereby the two parasite strains, known as forest and savanna, are preferentially transmitted by distinct groups of the species of S damnosum S l.

METHODS

During 1993 and 1994, wild black flies were collected from 11 river basins within the area covered by the Onchocerciasis Control Programme (OCP). The flies were dissected and filarial larvae, ovaries, and malpighian tubules removed. Genomic DNA was extracted from larvae, and PCR amplification was used to classify O volvulus parasites as forest or savanna strains. PCR-amplified DNA from ovaries and malpighian tubules was used to distinguish sibling species of S damnosum s l. S yahense and S squamosum were distinguished by body colour.

FINDINGS

214 of 105105 flies dissected were infected with filarial larvae; 84 of these were infected with mature O volvulus parasites. Of the 35 savanna-dwelling infected flies. 17 carried forest-strain parasites and 18 savanna-strain parasites. Of the 45 infected flies identified as the forest dwelling sibling species. 20 carried savanna-strain parasites and 25 forest-strain parasites. No significant differences were found in the numbers of mature larvae of each strain carried by the forest-dwelling species of fly or in the number of forest and savanna larvae in savanna-dwelling vector species.

INTERPRETATION

Vector-parasite transmission complexes do not currently play a part in the biology of O volvulus transmission in the area of the OCP in West Africa. This finding has important strategic implications for the future of efforts to control onchocerciasis in West Africa.

The Simulium damnosum species complex: phylogenetic analysis and molecular identification based upon mitochondrially encoded gene sequences

The DNA sequence of portions of the 16s rRNA and the NADH dehydrogenase subunit 4 (ND4) genes were used to determine phylogenetic relationships in the Simulium damnosum s.l. species complex. Results suggested that at least two major clades existed in the S. damnosum species complex, and that members of the S. damnosum s.l. species complex were not closely related to North American Simulium species. The sequence variability of the ND4 gene was exploited to develop a method to distinguish the sibling species of the S. damnosum s.l. species complex, based on directed heteroduplex analysis of PCR products derived from the ND4 gene. This method was capable of classifying the six sibling species into at least five groups.

Automatic computed tomography patient dose calculation using DICOM header metadata

The present work describes a method that calculates the patient dose values in computed tomography (CT) based on metadata contained in DICOM images in support of patient dose studies. The DICOM metadata is preprocessed to extract necessary calculation parameters. Vendor-specific DICOM header information is harmonized using vendor translation tables and unavailable DICOM tags can be completed with a graphical user interface. CT-Expo, an MS Excel application for calculating the radiation dose, is used to calculate the patient doses. All relevant data and calculation results are stored for further analysis in a relational database. Final results are compiled by utilizing data mining tools. This solution was successfully used for the 2009 CT dose study in Luxembourg. National diagnostic reference levels for standard examinations were calculated based on each of the countries' hospitals. The benefits using this new automatic system saved time as well as resources during the data acquisition and the evaluation when compared with earlier questionnaire-based surveys.

Perspectives on the bacterial control of vectors in the tropics

Biological agents have not found wide application in the control of insects that transmit agents of human disease. Fungal pathogens may have a potential for field use, but environmental constraints, lack of knowledge of their life cycle, or dependence on production in vivo, have prevented their widespread use. In fact, sporogenous bacteria are the only biological agents used on a large scale for the control of mosquitoes and blackflies that transmit diseases in the tropics. Two bacteria, Bacillus thuringiensis sp. israelensis and B. sphaericus are very effective for the control of these vectors. In this article, Jean Marc Hougard and Christian Back discuss various factors associated with the use of bacteria for vector control, and the prospects for further developments.

The Streptococcus gordonii Adhesin CshA Protein Binds Host Fibronectin via a Catch-Clamp Mechanism

Adherence of bacteria to biotic or abiotic surfaces is a prerequisite for host colonization and represents an important step in microbial pathogenicity. This attachment is facilitated by bacterial adhesins at the cell surface. Because of their size and often elaborate multidomain architectures, these polypeptides represent challenging targets for detailed structural and functional characterization. The multifunctional fibrillar adhesin CshA, which mediates binding to both host molecules and other microorganisms, is an important determinant of colonization by Streptococcus gordonii, an oral commensal and opportunistic pathogen of animals and humans. CshA binds the high-molecular-weight glycoprotein fibronectin (Fn) via an N-terminal non-repetitive region, and this protein-protein interaction has been proposed to promote S. gordonii colonization at multiple sites within the host. However, the molecular details of how these two proteins interact have yet to be established. Here we present a structural description of the Fn binding N-terminal region of CshA, derived from a combination of X-ray crystallography, small angle X-ray scattering, and complementary biophysical methods. In vitro binding studies support a previously unreported two-state "catch-clamp" mechanism of Fn binding by CshA, in which the disordered N-terminal domain of CshA acts to "catch" Fn, via formation of a rapidly assembled but also readily dissociable pre-complex, enabling its neighboring ligand binding domain to tightly clamp the two polypeptides together. This study presents a new paradigm for target binding by a bacterial adhesin, the identification of which will inform future efforts toward the development of anti-adhesive agents that target S. gordonii and related streptococci.

Topical application of diethylcarbamazine to detect onchocerciasis recrudescence in west Africa

The Onchocerciasis Control Programme in West Africa (OCP) has succeeded in eliminating blinding onchocerciasis as a public health problem throughout much of West Africa. The efforts of the OCP are now turning towards surveillance, with the goal of rapidly detecting and controlling outbreaks of infection in the onchocerciasis-free zone. With this goal in mind, cutaneous application of a solution of diethylcarbamazine (the DEC-patch test) was evaluated in 1996-99 as a method to detect patent Onchocerca volvulus infection in children and adolescents, a sentinel population for the detection of recrudescence. In an analysis of 1887 individuals in Côte d'Ivoire and Burkina Faso, the DEC-patch test produced prevalence estimates comparable to those obtained by skin snip. The sensitivity of the DEC-patch assay was marginally greater in children and adolescents than in adults, and was greater in individuals who had received prior Mectizan treatment. These data suggest that the DEC-patch test may be a useful tool for detecting recrudescence of O. volvulus infection in a sentinel population of children and young adults within the onchocerciasis-free zone created by the OCP.

NMR rheotomography: feasibility and clinical potential

An investigation has been undertaken of the effect of flow on NMR images. We term the new technique of flow analysis examined here, NMR rheotomography. Images were acquired through use of a spin-echo technique. They were of doped water passing through a glass U-tube, simulating a small vein, which fitted into the magnetic field gradient and radiofrequency coils of an NMR imaging apparatus. For the case of the inlet arm of the U-tube, the flow images displayed an intensity distribution which compared favorably to a simple physical model based on laminar flow. The intensity distribution observed for the outlet arm was explained through consideration of the perturbation to flow introduced by the U-bend. Generally, the results of the feasibility study indicate that (a) the NMR spin-echo image is modified by flow in a predictable manner, (b) display of the velocity profile is possible, (c) through use of a U-tube some separation can be demonstrated within a single image of the twin factors, proton incursion into the image "slice" and proton dephasing, which generally combine to modify the flow image intensity, and (d) discrimination between different modes of flow may be possible by NMR CT. The clinical potential suggested by the results is discussed; NMR rheotomography may prove to be particularly useful for the noninvasive diagnosis of structurally-originating cardiovascular defects.

Death-inducing receptors and apoptotic changes in lymphocytes of patients with heart transplant vasculopathy

The specific role of lymphocyte apoptosis and transplant-associated atherosclerosis is not well understood. The aim of our study was to investigate the impact of T cell apoptotic pathways in patients with heart transplant vasculopathy. Amongst 40 patients with cardiac heart failure class IV who have undergone heart transplantation, 20 recipients with transplant-associated coronary artery disease (TACAD) and 20 with non-TACAD were investigated one year postoperative. Expression of CD95 and CD45RO, and annexin V binding were measured by FACS. Soluble CD95, sCD95 ligand (sCD95L), tumour necrosis factor receptor type 1 (sTNFR1), and histones were measured in the sera by ELISA. The percentage of cells expressing CD3 and CD4 was significantly reduced in TACAD as well as in non-TACAD patients as compared with control volunteers. Interestingly, the proportion of CD19+ (B cells) and CD56+ (NK) cells was increased in TACAD groups (versus non-TACAD; P < 0.01, and P < 0.001, respectively). In contrast to sCD95, the expression of CD95 (APO-1/Fas) and CD45RO (memory T cells), and sCD95L were significantly increased in non-TACAD and TACAD patients. T cell activation via CD95 with consecutive apoptosis was increased in both groups. The concentration of sTNFR1, IL-10 and histones was significantly elevated in sera from TACAD than non-TACAD patients, and in both groups than in healthy controls. These observations indicate that the allograft may induce a pronounced susceptibility of CD4+ T cells to undergo apoptosis and antibody-driven activation-induced cell death. This data may suggest a paradox immune response similar to that seen in patients with autoimmune diseases.

Concerted functions of Streptococcus gordonii surface proteins PadA and Hsa mediate activation of human platelets and interactions with extracellular matrix

A range of Streptococcus bacteria are able to interact with blood platelets to form a thrombus (clot). Streptococcus gordonii is ubiquitous within the human oral cavity and amongst the common pathogens isolated from subjects with infective endocarditis. Two cell surface proteins, Hsa and Platelet adherence protein A (PadA), in S. gordonii mediate adherence and activation of platelets. In this study, we demonstrate that PadA binds activated platelets and that an NGR (Asparagine-Glycine-Arginine) motif within a 657 amino acid residue N-terminal fragment of PadA is responsible for this, together with two other integrin-like recognition motifs RGT and AGD. PadA also acts in concert with Hsa to mediate binding of S. gordonii to cellular fibronectin and vitronectin, and to promote formation of biofilms. Evidence is presented that PadA and Hsa are each reliant on the other's active presentation on the bacterial cell surface, suggesting cooperativity in functions impacting both colonization and pathogenesis.

Mitochondrial alleles of Simulium damnosum sensu lato infected with Onchocerca volvulus

Onchocerca volvulus infected Simulium damnosum s.l. were analysed by directed heteroduplex analysis. Of 73 infected flies, 68 produced heteroduplex products identical to those previously identified. All 6 major sibling species, except S. leonense, were present in this group. In the 5 remaining flies, 2 new heteroduplex patterns were noted. Molecular phylogenetic analysis of these samples suggested that they belonged to the S. squamosum/S. yahense subcomplex. The ability to reliably genotype adult flies will permit studies of the vectorial capacity of the sibling species of S. damnosum s.l. for the blinding and non-blinding strains of O. volvulus.

Utilization of Staphylococcal Immune Evasion Protein Sbi as a Novel Vaccine Adjuvant

Co-ligation of the B cell antigen receptor with complement receptor 2 on B-cells via a C3d-opsonised antigen complex significantly lowers the threshold required for B cell activation. Consequently, fusions of antigens with C3d polymers have shown great potential in vaccine design. However, these linear arrays of C3d multimers do not mimic the natural opsonisation of antigens with C3d. Here we investigate the potential of using the unique complement activating characteristics of Staphylococcal immune-evasion protein Sbi to develop a pro-vaccine approach that spontaneously coats antigens with C3 degradation products in a natural way. We show that Sbi rapidly triggers the alternative complement pathway through recruitment of complement regulators, forming tripartite complexes that act as competitive antagonists of factor H, resulting in enhanced complement consumption. These functional results are corroborated by the structure of the complement activating Sbi-III-IV:C3d:FHR-1 complex. Finally, we demonstrate that Sbi, fused with Mycobacterium tuberculosis antigen Ag85b, causes efficient opsonisation with C3 fragments, thereby enhancing the immune response significantly beyond that of Ag85b alone, providing proof of concept for our pro-vaccine approach.

Designer artificial membrane binding proteins to direct stem cells to the myocardium

We present a new cell membrane modification methodology where the inherent heart tissue homing properties of the infectious bacteria Streptococcus gordonii are transferred to human stem cells. This is achieved via the rational design of a chimeric protein-polymer surfactant cell membrane binding construct, comprising the cardiac fibronectin (Fn) binding domain of the bacterial adhesin protein CshA fused to a supercharged protein. Significantly, the protein-polymer surfactant hybrid spontaneously inserts into the plasma membrane of stem cells without cytotoxicity, instilling the cells with a high affinity for immobilized fibronectin. Moreover, we show that this cell membrane reengineering approach significantly improves retention and homing of stem cells delivered either intracardially or intravenously to the myocardium in a mouse model.

Evidence of multiple mating and hybridization in Simulium damnosum s.l. (Diptera: Simuliidae) in nature

Beakers with aeration were used to rear individual (single) egg batches of Simulium damnosum (Theobald) s.l. to larvae and adults. Chromosomal analysis of the progeny of individual females indicated that multiple mating occurred within the S. damnosum complex and that hybridization occurred between S. damnosum s.s. and S. sirbanum (Vajime & Dunbar) in nature. These results indicate that possibly more extensive hybridization may be taking place in some areas of the Onchocerciasis Control Program than previously reported. Dramatic changes in the rates of hybridization among members of the S. damnosum complex possibly may lead to the formation of new cytotypes.