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Interacción parásito-hospedador en fasciolosis ovina: mecanismos de respuesta en fases tempranas y tardías
Get PDFFasciola hepatica es el agente etiológico de la fasciolosis, enfermedad
descrita como la principal causa de pérdidas económicas en el sector
agrícola y ganadero en países desarrollados y en vías de desarrollo como
consecuencia de las tasas de morbilidad y mortalidad que origina en los
animales de abasto. La OMS la describe como una enfermedad
parasitaria re-emergente con un especial impacto en humanos alrededor
de todo el mundo.
Entre los distintos principios activos disponibles para hacer frente a esta
enfermedad, el triclabendazol se erigió como el fármaco de elección en
el tratamiento de la fasciolosis. Debido al uso de antihelmínticos como
único medio eficaz para el control de la infección, se hace necesario el
estudio e implementación de vías alternativas que permitan el control de
esta enfermedad, como la obtención de líneas genéticas resistentes o el
desarrollo de vacunas.
La infección por F. hepatica desencadena la actuación de la respuesta
inmunitaria como consecuencia del reconocimiento de numerosos
antígenos de excreción-secreción (FhESPs) o de la superficie del
parásito. Estas moléculas han sido identificadas y purificadas con el fin
de realizar ensayos vacunales con los que determinar su capacidad
inmunógena y qué antígeno pudiera constituir el candidato idóneo de una
vacuna eficaz. La mayoría de los estudios vacunales realizados en rumiantes se han centrado en el empleo de antígenos obtenidos a partir
de la fase adulta del parásito, si bien se torna de vital importancia
identificar áquellos que juegan un papel relevante durante todas las fases
de la infección.
Con este motivo, se empleó en un primer estudio un antígeno (rFh14-
3-3z) de la familia de proteínas 14-3-3, con el que poder determinar el
perfil inmunológico y el componente parasitológico, haciendo hincapié
en el número de fasciolas asentadas en hígado y la dinámica de
eliminación de huevos en heces.
Se usaron 24 ovejas de raza merina de seis meses de edad divididas
aleatoriamente en tres grupos (n=8) con el siguiente modelo: el grupo 1
fue inmunizado con la proteína recombinante Fh14-3-3z y el adyuvante
Montanide™ ISA 71 VG, el grupo 2 se inmunizó únicamente con
Montanide™ ISA 71 VG (control adyuvante) y el grupo 3 fue el grupo
control de infección (infectado y no vacunado). Ocho semanas
posteriores a la primera inmunización los animales fueron infectados
oralmente con una única dosis de 150 metacercarias. A las 6 semanas de
la infección se realizó un muestreo de heces semanalmente a todos los
animales para analizar la dinámica de eliminación de huevos mediante
McMaster con sulfato de zinc. La presencia de huevos en heces se
detectó a las 8 semanas post-infección en el grupo 1 y las 9 semanas en los grupos 2 y 3. De la misma manera, una vez sacrificados se recogieron
los adultos de F. hepatica de los hígados para realizar su recuento, así
como la medición de los vermes. El grupo 1 presentó una carga de 52’25
± 16’71 fasciolas, similar al grupo 3 con una carga media de 51’13 ±
12’84 y el grupo 2 evidenció una mayor carga parasitaria con 68’13 ±
23’79 adultos. La respuesta inmunitaria humoral, para los isotipos IgG1
e IgG2, analizada mediante ELISA indirecto mostró un incremento
significativo en IgG1 tres semanas después de la inmunización, mientras
que IgG2 aumenta su producción significativamente únicamente después
de la inmunización en el grupo 2.
Debido a los ensayos que han demostrado la falta de protección en
animales inmunizados con diferentes antígenos de F. hepatica y a la
capacidad inmunomoduladora del parásito se hace necesario conocer la
respuesta inmunitaria que se desencadena en las primeras fases de la
infección. Por ello, el segundo estudio tuvo como objetivo el análisis
poblacional de linfocitos (TCD4, TCD8 y WC1+γδ), macrófagos
(CD14), MHCII como célula presentadora de antígenos y células
dendríticas (CD83) de cavidad peritoneal de animales infectados y
sacrificados en fases iniciales y tardías. En este ensayo se emplearon 37
ovejas de raza merina de seis meses de edad, las cuales fueron divididas
aleatoriamente en tres grupos atendiendo al momento del sacrificio: el grupo 1 (n=20) (estadios tempranos) y grupo 2 (n=10) (estadios tardíos)
fueron infectados con una dosis de 150 metacercarias. Los animales del
grupo 1 fueron sacrificados a los 1, 3, 9 y 18 días post-infección (dpi),
así mismo, el grupo 2 fueron sacrificados a las 14 semanas post-infección
(spi). El grupo 3 no se infectó y se describió como grupo control
negativo. Los parámetros parasitológicos del grupo 2 mostraron una
carga parasitaria de 67’78 ± 13’85 adultos con una tasa de implantación
con niveles de 45’19% ± 9’24. La presencia de huevos en heces se
detectó a las 8 semanas de la infección, alcanzando su máximo a la
semana 13. El análisis de las distintas poblaciones leucocitarias se
determinó mediante citometría de flujo con distintos anticuerpos
monoclonales. Los animales sacrificados en las fases tempranas
únicamente mostraron un descenso significativo de los TCD4 a los 1 y
18 dpi. Asimismo, la población de CD14 peritoneal evidenció un
descenso a las 9 y 18 dpi, mientras que MHCII y CD83 describen un
patrón similar con una significativa disminución a los 3 y 9 dpi. Los
animales sacrificados a las 14 semanas aumentaron significativamente
su población de WC1+γδ pero sufrieron un descenso significativo en las
subpoblaciones de macrófagos y células dendríticas peritoneales.
Continuando con una mejor compresión de los mecanismos defensivos
del hospedador frente a esta enfermedad, el tercer trabajo realizado tuvo como objetivo analizar la dinámica poblacional en líquido
peritoneal y la producción de radicales libres en animales infectados y
vacunados. Para este estudio se emplearon 45 ovejas de raza merina de
seis meses de edad agrupadas aleatoriamente como se describe: el grupo
1 (n=5) fueron animales no infectados ni vacunados y fue descrito como
grupo control negativo, el grupo 2 (n=20) fue experimentalmente
infectado con 150 metacercarias y el grupo 3 (n=20) fue inmunizado con
rFhCL1 e infectado con 150 metacercarias. El grupo 1 fue sacrificado a
las 12 spi mientras que los grupos 2 y 3 fueron sacrificados a los 1, 3, 9
y 18 dpi. La respuesta inmunitaria humoral evidenció diferencias
significativas en IgG1 desde las 6ª semana post-vacunación en el grupo
3 y únicamente a los 1 dpi para IgG2. El número total de leucocitos
reveló un aumento significativo a los 9 y 18 dpi para el grupo 2 y 3. Más
específicamente, el grupo 2 evidenció un aumento significativo de
granulocitos a los 9 dpi y de las tres poblaciones peritoneales a los 18
dpi. Por su parte, el grupo 3 aumentó el número de linfocitos a los 3 y 18
dpi, así como la población de macrófagos y granulocitos a los 9 y 18 dpi.
La medición de radicales libres por parte de los leucocitos se determinó
mediante citometría de flujo usando 2 reactivos diferentes: DAF-2DA
para el óxido nítrico y DCFH-DA para el peróxido de hidrógeno. En
relación a la producción H2O2, el grupo 2 incrementó su producción por parte de los macrófagos a los 3 y 9 dpi, y a los 18 dpi por parte de los
granulocitos. Asimismo, los granulocitos en el grupo 3 mostraron un
aumento de este radical libre a los 9 y 18dpi. Finalmente, la producción
de NO en el grupo 2 sufrió un incremento significativo por parte de los
granulocitos a los 9 y 18 dpi y en los macrófagos a los 18 dpi. Sin
embargo, el grupo 3 aumentó la producción de NO a los 3 dpi por parte
de los macrófagos y a los 3, 9 y 18 dpi en los granulocitos.Fasciola hepatica is the ethyological agent of fasciolosis, a disease
described as the major cause of economic losses to the agricultural
industry in developed and developing countries due to the high morbility
and mortility rates in livestock. It has been described as a tropical reemerging
disease by the WHO.
Triclabendazole is the drug of choice against fasciolosis, among different
drugs available for the control of the disease. Due to the use of
anthelmintic as the only effective mean for the control of the infection,
alternative ways for disease control are required, as genetically resistant
species or the development of vaccines.
Fasciola hepatica infection triggers the immune response as a
consequence of the recognition of numerous excretory and secretory
products (FhESPs) or tegumental proteins. These molecules have been
identified and purified in order to perform vaccine trials aimed at
determining their immunogenic capacity so as to develop a vaccine.
Most of the vaccine trials carried out in ruminants had been conducted
using the adult fluke antigens that are exposed to the immune system.
Therefore, it is essential to identify the molecules that play a key role
during the course of infection. On this reason, an antigen from the 14-3-3 protein family (14-3-3z) has
been used in a first study. With the use of rFh14-3-3z antigen we
determined the immunological and parasitological parameters since the
first vaccination, with special attention to the number of adult flukes in
the liver and the dynamic of faecal egg count.
Twenty-four female Merino-breed sheep 6 month old were used for the
study. Sheep were randomly allocated into three groups (n=8). Animals
from group 1 were immunised with the recombinant antigen rFh14-3-3z
in Montanide adjuvant (Montanide™ISA 71 VG -Seppic®). Group 2
was immunised with Montanide adjuvant (adjuvant control group) and
animals from group 3 were not immunised and remained as positive
infection control. Eight weeks after first immunisation all animals were
orally challenged with a single dose of 150 metacercariae of F. hepatica.
To assess egg output, faecal samples were individually collected weekly
from week six after challenge until the end of the trial, and were analysed
by a zinc sulphate-based flotation method using the McMaster chamber.
Eggs were first detected at 8 wpi in group 1 and 9 wpi in group 2 and 3.
Once sheep were slaughtered the livers were collected and the adult
flukes were recovered for measurement and weighing. Fluke burden of
group 1 was 52’25 ± 16’71, similar to the group 3 with a mean of 51’13
± 12’84 adult flukes. The group 2 showed a higher fluke burden of 68’13 ± 23’79 adults. On regard to the humoral immune system, indirect
ELISA showed a significant increase of IgG1 at week 3 after
immunisation, while IgG2 increased significantly its values only after
immunisation in group 2.
Due to the failure of many vaccination trials using broad variety of F.
hepatica antigens and to the immunomodulatory capacity of the liver
flukes, the study of the immune response during the early stages of the
infection is vital for a better understanding of the immunological
pathways elicited during the host-parasite interaction.
Thus, the second study was aimed at analysing the peritoneal lymphocyte
(TCD4, TCD8 and WC1+γδ), macrophage (CD14), MHCII as an antigen
presenting cell, and dendritic cells (CD83) populations of infected
animals and slaughtered at the early and late stages of infection.
Thirty-seven female Merino-breed sheep, aged 6 months, were used for
the study. Animals were randomly allocated into 3 groups according to
the slaughtering time: group 1 (n=20) (early stage) and group 2 (n=10)
(late stage) were infected with a single dose of 150 metacercariae. Sheep
from group 1 were sacrified at 1, 3, 9 and 18 days post-infection (dpi).
In the same way, animals from group 2 were slaughtered at 14 weeks
post-infection (spi). The group 3 was not infected and remained as a negative control group. Parasitological parameters from group 2 showed
a fluke burden of 67’78 ± 13’85 adults with a implantation rate of
45’19% ± 9’24. Eggs in faecal samples were first detected at week 8
post-infection, reaching the highest figures at 13 wpi. The analysis of the
different leukocyte populations was determined by flow cytometry with
diverse monoclonal antibodies. Animals sacrified at the early stages of
infection only showed a significant decrease of TCD4 at 1 and 18 dpi.
Furthermore, CD14 peritoneal population showed a decrease at 9 and 18
dpi, while MHCII and CD83 described a similar pattern with a
significant decrease at 3 and 9 dpi. Animals slaughtered at 14 wpi
increase significantly WC1+γδ subpopulation but macrophage and
dendritic cells peritoneal populations showed a significant decrease.
Continuing with a better understanding of host immunological
mechanisms against the disease, our third study aimed to analyse the
dynamic of peritoneal populations and the production of free radicals in
immunised and infected animals. For this study, Forty-five six-monthold
male merino sheep were used and randomly allocated as described:
group 1 (n=5) was not infected and not vaccinated and remained as
negative control group, group 2 (n=20) was experimentally infected with
150 metacercariae and group 3 (n=20) was immunised with rFhCL1 and
infected with 150 metacercariae. Group 1 was slaughtered at 12 wpi, while groups 2 and 3 were sacrified at 1, 3, 9 and 18 dpi. Humoral
immune response showed significant differences in IgG1 at 6 postimmunisation
in group 3 and only at 1 dpi for IgG2. Total number of
leukocytes revealed a significant increase at 9 and 18 dpi for group 2 and
3. Granulocytes from group 2 increased significantly at 9 dpi and the
three peritoneal populations at 18 dpi. Group 3 increased the number of
lymphocytes at 3 and 18 dpi, as well as macrophage and granulocyte
populations at 9 and 18 dpi. Free radical measurement was determined
with flow cytometry analysis using two different reagent: DAF-2DA for
nitric oxide and DCFH-DA for hydrogen peroxide. In relation to H2O2
production, macrophages from group 2 increased the production at 3 and
9 dpi, and granulocytes at 18 dpi. Finally, NO production in group 2
increased significantly in granulocytes at 9 and 18 dpi and in
macrophages at 18 dpi. However, group 3 increased NO production at 3
dpi in macrophages and at 3, 9 and 18 dpi in granulocytes
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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