217 research outputs found

    Tissue Harvester with Functional Valve (THFV): Shidham's device for reproducibly higher specimen yield by fine needle aspiration biopsy with easy to perform steps

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    BACKGROUND: Fine needle aspiration biopsy (FNAB) cytology has been a highly effective methodology for tissue diagnosis and for various ancillary studies including molecular tests. In addition to other benefits, FNAB predominantly retrieves the diagnostic loosely cohesive cells in the lesion as compared to the adjacent supporting stroma with relatively higher cohesiveness. However, FNAB procedure performed with currently available resources is highly skill dependent with inter-performer variability, which compromises its full potential as a diagnostic tool. In this study we report a device overcoming these limitations. METHODS: 'Tissue Harvester with Functional Valve' (THFV) was evaluated as part of a phase 1 National Institute of Health (NIH) research grant under Small Business Technology Transfer (STTR) Program. Working prototypes of the device were prepared. Each of the four cytopathologists with previous cytopathology fellowship training and experience in performing FNAB evaluated 5 THFV and 5 hypodermic needles resulting in 40 specimens (20 with THFV, 20 with hypodermic needles). A piece of fresh cattle liver stuffed in latex glove was used as the specimen. Based on these results a finished design was finalized. RESULTS: The smears and cell blocks prepared from the specimens obtained by THFV were superior in terms of cellularity to specimens obtained with hypodermic needles. The tissuecrit of specimens obtained with THFV ranged from 70 to 100 μl (mean 87, SD 10), compared to 17 to 30 μl (mean 24, SD 4) with conventional hypodermic needles (p < .0001, Student t-test). The technical ease [on a scale of 1 (easy) to 5 (difficult)] with THFV ranged from 1 to 2 as compared to 2 to 3 with hypodermic needles. CONCLUSION: The specimen yield with the new THFV was significantly higher when compared to hypodermic needles. Also, the FNAB procedure with THFV was relatively easier in comparison with hypodermic needles. The final version of Shidham's THFV device would improve the FNAB specimen yield by eliminating the skill factor. The increased specimen yield by this device would also facilitate wider application of FNAB specimens for various ancillary tests, including molecular tests

    Investigating the Host Binding Signature on the Plasmodium falciparum PfEMP1 Protein Family

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    The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family plays a central role in antigenic variation and cytoadhesion of P. falciparum infected erythrocytes. PfEMP1 proteins/var genes are classified into three main subfamilies (UpsA, UpsB, and UpsC) that are hypothesized to have different roles in binding and disease. To investigate whether these subfamilies have diverged in binding specificity and test if binding could be predicted by adhesion domain classification, we generated a panel of 19 parasite lines that primarily expressed a single dominant var transcript and assayed binding against 12 known host receptors. By limited dilution cloning, only UpsB and UpsC var genes were isolated, indicating that UpsA var gene expression is rare under in vitro culture conditions. Consequently, three UpsA variants were obtained by rosette purification and selection with specific monoclonal antibodies to create a more representative panel. Binding assays showed that CD36 was the most common adhesion partner of the parasite panel, followed by ICAM-1 and TSP-1, and that CD36 and ICAM-1 binding variants were highly predicted by adhesion domain sequence classification. Binding to other host receptors, including CSA, VCAM-1, HABP1, CD31/PECAM, E-selectin, Endoglin, CHO receptor “X”, and Fractalkine, was rare or absent. Our findings identify a category of larger PfEMP1 proteins that are under dual selection for ICAM-1 and CD36 binding. They also support that the UpsA group, in contrast to UpsB and UpsC var genes, has diverged from binding to the major microvasculature receptor CD36 and likely uses other mechanisms to sequester in the microvasculature. These results demonstrate that CD36 and ICAM-1 have left strong signatures of selection on the PfEMP1 family that can be detected by adhesion domain sequence classification and have implications for how this family of proteins is specializing to exploit hosts with varying levels of anti-malaria immunity

    Electronic states and phases of KxC60 from photoemission and X-ray absorption spectroscopy

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    HIGH-resolution photoemission and soft X-ray absorption spectroscopies have provided valuable information on the electronic structure near the Fermi energy in the superconducting copper oxide compounds 1-4, helping to constrain the possible mechanisms of superconductivity. Here we describe the application of these techniques to K(x)C60, found recently to be superconducting below 19.3 K for x almost-equal-to 3 (refs 5-7). The photoemission and absorption spectra as a function of x can be fitted by a linear combination of data from just three phases, C60, K3C60, and K6C60, indicating that there is phase separation in our samples. The photoemission spectra clearly show a well defined Fermi edge in the K3C60 phase with a density of states of 5.2 x 10(-3) electrons eV-1 angstrom-3 and an occupied-band width of 1.2 eV, suggesting that this phase may be a weakly coupled BCS-like (conventional) superconductor. The C1s absorption spectra show large non-rigid-band shifts between the three phases with half and complete filling, in the K3C60 and K6C60 phases respectively, of the conduction band formed from the lowest unoccupied molecular orbital of C60. These observations clearly demonstrate that the conduction band has C 2p character. The non-rigid-band shift coupled with the anomalous occupied-band width implies that there is significant mixing of the electronic states of K and C60 in the superconducting phase

    Simplified mathematical model of proton exchange membrane fuel cell based on horizon fuel cell stack

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    This paper presents a simplified zero-dimensional mathematical model for a self-humidifying proton exchange membrane (PEM) fuel cell stack of 1 kW. The model incorporates major electric and thermodynamic variables and parameters involved in the operation of the PEM fuel cell under different operational conditions. Influence of each of these parameters and variables upon the operation and the performance of the PEM fuel cell are investigated. The mathematical equations are modeled by using Matlab–Simulink tools in order to simulate the operation of the developed model with a commercial available 1 kW horizon PEM fuel cell stack (H-1000), which is used for the purposes of model validation and tuning of the developed model. The model can be extrapolated to higher wattage fuel cells of similar arrangements. New equation is presented to determine the impact of using air to supply the PEM fuel cell instead of pure oxygen upon the concentration losses and the output voltage when useful current is drawn from it

    What the Public Was Saying about the H1N1 Vaccine: Perceptions and Issues Discussed in On-Line Comments during the 2009 H1N1 Pandemic

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    During the 2009 H1N1 pandemic, a vaccine was made available to all Canadians. Despite efforts to promote vaccination, the public's intent to vaccinate remained low. In order to better understand the public's resistance to getting vaccinated, this study addressed factors that influenced the public's decision making about uptake. To do this, we used a relatively novel source of qualitative data – comments posted on-line in response to news articles on a particular topic. This study analysed 1,796 comments posted in response to 12 articles dealing with H1N1 vaccine on websites of three major Canadian news sources. Articles were selected based on topic and number of comments. A second objective was to assess the extent to which on-line comments can be used as a reliable data source to capture public attitudes during a health crisis. The following seven themes were mentioned in at least 5% of the comments (% indicates the percentage of comments that included the theme): fear of H1N1 (18.8%); responsibility of media (17.8%); government competency (17.7%); government trustworthiness (10.7%); fear of H1N1 vaccine (8.1%); pharmaceutical companies (7.6%); and personal protective measures (5.8%). It is assumed that the more frequently a theme was mentioned, the more that theme influenced decision making about vaccination. These key themes for the public were often not aligned with the issues and information officials perceived, and conveyed, as relevant in the decision making process. The main themes from the comments were consistent with results from surveys and focus groups addressing similar issues, which suggest that on-line comments do provide a reliable source of qualitative data on attitudes and perceptions of issues that emerge in a health crisis. The insights derived from the comments can contribute to improved communication and policy decisions about vaccination in health crises that incorporate the public's views

    Two-dimensional transport and transfer of a single atomic qubit in optical tweezers

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    Quantum computers have the capability of out-performing their classical counterparts for certain computational problems1. Several scalable quantum-computing architectures have been proposed. An attractive architecture is a large set of physically independent qubits arranged in three spatial regions where (1) the initialized qubits are stored in a register, (2) two qubits are brought together to realize a gate and (3) the readout of the qubits is carried out2, 3. For a neutral-atom-based architecture, a natural way to connect these regions is to use optical tweezers to move qubits within the system. In this letter we demonstrate the coherent transport of a qubit, encoded on an atom trapped in a submicrometre tweezer, over a distance typical of the separation between atoms in an array of optical traps4, 5, 6. Furthermore, we transfer a qubit between two tweezers, and show that this manipulation also preserves the coherence of the qubit

    Allelic Diversity of the Plasmodium falciparum Erythrocyte Membrane Protein 1 Entails Variant-Specific Red Cell Surface Epitopes

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    The clonally variant Plasmodium falciparum PfEMP1 adhesin is a virulence factor and a prime target of humoral immunity. It is encoded by a repertoire of functionally differentiated var genes, which display architectural diversity and allelic polymorphism. Their serological relationship is key to understanding the evolutionary constraints on this gene family and rational vaccine design. Here, we investigated the Palo Alto/VarO and IT4/R29 and 3D7/PF13_003 parasites lines. VarO and R29 form rosettes with uninfected erythrocytes, a phenotype associated with severe malaria. They express an allelic Cys2/group A NTS-DBL1α1 PfEMP1 domain implicated in rosetting, whose 3D7 ortholog is encoded by PF13_0003. Using these three recombinant NTS-DBL1α1 domains, we elicited antibodies in mice that were used to develop monovariant cultures by panning selection. The 3D7/PF13_0003 parasites formed rosettes, revealing a correlation between sequence identity and virulence phenotype. The antibodies cross-reacted with the allelic domains in ELISA but only minimally with the Cys4/group B/C PFL1955w NTS-DBL1α. By contrast, they were variant-specific in surface seroreactivity of the monovariant-infected red cells by FACS analysis and in rosette-disruption assays. Thus, while ELISA can differentiate serogroups, surface reactivity assays define the more restrictive serotypes. Irrespective of cumulated exposure to infection, antibodies acquired by humans living in a malaria-endemic area also displayed a variant-specific surface reactivity. Although seroprevalence exceeded 90% for each rosetting line, the kinetics of acquistion of surface-reactive antibodies differed in the younger age groups. These data indicate that humans acquire an antibody repertoire to non-overlapping serotypes within a serogroup, consistent with an antibody-driven diversification pressure at the population level. In addition, the data provide important information for vaccine design, as production of a vaccine targeting rosetting PfEMP1 adhesins will require engineering to induce variant-transcending responses or combining multiple serotypes to elicit a broad spectrum of immunity
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