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Embryonation ability of Ascaridia galli eggs isolated from worm uteri or host faeces
No full textExperimental infection models for Ascaridia galli rely on the use of eggs isolated either directly from worm uteri or from host faeces. We investigated whether A. galli eggs isolated from the two sources differ in their embryonation ability. A. galli eggs originating from 12 worm infrapopulations were isolated both from faeces of the living host (faecal eggs) and directly from worm uteri after host necropsy (uterine eggs). The isolated eggs from each infrapopulation and source were incubated in Petri dishes (n = 24) containing a potassium-dichromate (0.1%) medium for 28 days (d) at room temperature. Starting from the day of egg isolation (d0), in ovo larval development was evaluated every second day by examining morphological characteristics of 200 eggs/petri dish. A total of 72,000 eggs were classified into undeveloped, early development, vermiform or fully embryonated stages. Isolation procedures caused similar damage to uterine and faecal eggs (2.2% and 0.5%, respectively; P=0.180). The first sign of in ovo embryonic development in faecal eggs (7%) was observed during the 24-h period when faeces were collected. On d28, a higher percentage of uterine eggs remained undeveloped when compared with faecal eggs (58.6% vs 11.0%; P<0.001). Although a higher (P<0.001) percentage of faecal eggs entered both the early developmental and vermiform stages, which took place primarily within the first two weeks of incubation, there was no time-shift between the development of faecal and uterine eggs. Starting from day 10, higher (P<0.05) percentages of faecal eggs completed embryonation compared with uterine equivalents. Eggs from both sources reached a plateau of embryonation by the end of 2nd week of incubation, with faecal eggs having a greater than two-fold higher embryonation ability. Cumulative mortality was higher in uterine eggs (14.3%) than in faecal eggs (0.2%). We conclude that faecal eggs have a higher embryonation ability than uterine eggs possibly due to maturation differences. (C) 2015 Elsevier B.V. All rights reserved.Erasmus Mundus projec
Maternal protection against Ascaridia galli?
No full textMaternally derived antibodies can provide partial protection against certain bacterial and viral infections. We investigated whether chicks descending from nematode-infected hens are more resistant against Ascaridia galli, a prevalent gastrointestinal nematode, than chicks from nematode-free mothers. One day -old chicks (N=153) from infected (mab+; maternal antibody+) or uninfected control dams (mab-) were experimentally infected with A. galli at two different levels (100 or 1000 eggs/chick). The worm burdens of the chicks were determined at 6 weeks post infection. There was a high correlation (r=0.89) between A. galli-specific antibody concentrations in dam plasma and egg yolk. There was no difference between worm burdens of chicks descending from infected or uninfected dams (P=0.892), indicating no maternally derived protection against A. galli. Chicks receiving the higher infection dose had higher worm burdens (P0.05) between worm counts of female and male chicks infected with 100 eggs, females chicks infected with 100 eggs harboured longer and heavier female worms. We conclude that there is no protective maternal immunity against A. galli infection. (C) 2016 Elsevier B.V. All rights reserved.Erasmus Mundus projec
A comprehensive evaluation of an ELISA for the diagnosis of the two most common ascarids in chickens using plasma or egg yolks
No full textBACKGROUND:
Classical faecal egg counts (FEC) provide less reliable diagnostic information for nematode infections in chickens. We developed an ELISA based on Ascaridia galli antigens and tested two hypotheses, as follows: (i) IgY antibodies developed against A. galli will also be useful to identify Heterakis gallinarum infections, and (ii) circulating antibodies stored in egg yolks are as good as plasma samples, so a non-invasive diagnosis is possible. The aim of this study, therefore, was to compare the diagnostic accuracy of the ELISA system with FEC, using both plasma and egg yolks from experimentally infected hens. In addition, naturally infected animals were evaluated to validate the assay.
RESULTS:
The assay quantified large differences (P < 0.001) in plasma or in egg-yolk IgY concentrations between infected and uninfected animals in two experiments, each performed with either of the nematode species. The assay performed with high accuracy as quantified with the area under the ROC curve (AUC) values of > 0.90 for both nematodes using either plasma or egg yolks. Sensitivity of the assay was 94 and 93% with plasma and egg yolk samples, respectively, whereas FEC yielded in a sensitivity of 84% in A. galli experiment. Total test accuracy of the assay with plasma samples (AUC = 0.99) tended to be higher (P = 0.0630) than FEC (AUC = 0.92) for A. galli, while the assay with either sample matrix performed similar to FEC (AUC ≥ 0.91) for H. gallinarum. Among the three tests, the FECs correlated better with A. galli burden than the ELISA. Although 90% of naturally infected hens were correctly identified by the ELISA, 45% of the infected hens tested negative with FEC, indicating the validity of the higher test accuracy of the ELISA.
CONCLUSIONS:
Antigens of A. galli can be used successfully to identify H. gallinarum-infected animals, indicating that chickens develop cross-reactive antibodies against the two closely related species. Egg yolks are as informative as plasma samples, so that animal welfare-friendly sampling is possible. Although the assay with plasma samples reveals qualitative information of higher quality than FECs on the infection status of naturally infected birds, the latter is still a better tool to assess the intensity of A. galli but not of H. gallinarum infections
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Studies on the Ascaridia galli embryonal stages, potential maternal protection and immune response in chicken
Full text linkRegarding to a lack of experimental infection models and different maturation ability
of Ascaridia galli egg sources (Worm uteri and faeces) in a first study (Paper 1),
A.galli eggs isolated from two different sources were investigated for different
embryonic development capacities. The second study (Paper 2) showed no
protective maternal immunity against A. galli in chicken. The objective was to
investigate whether maternal antibody positive chicks are more resistant to A. galli
infection than maternal antibody negative chicks. Free-range chickens are exposed
to a high risk of nematode infections. Genetic selection for increased immunity could
be an important tool to reduce problems due to infectious diseases - estimating the
number of parasite eggs for an infectivity diagnosis can be unreliable in a free-range
system. Thus the objectives of a third study (Paper 3) were to estimate genetic
resistance to naturally acquired immune systems and infectivity diagnosis by
estimating the total specific antibody responses against most prevalent nematodes in
the free-range laying hen system.
The first experiment (Paper 1) was performed to investigate the embryonation ability
of A. galli eggs, isolated from two different sources originating from 12 worm
infrapopulations both from faeces of the living host (faecal eggs) and directly from
worm uteri after host necropsy (uterine eggs). The isolated eggs from each
infrapopulation and source were incubated in Petri dishes (n=24) containing a
potassium-dichromate (0.1%) medium for 28 days at room temperature. In ovo larval
development was evaluated every second day by examining morphological
characteristics of 200 eggs/ Petri dish starting from the day of egg isolation (d0). A
total of 72,000 eggs were classified into undeveloped, early development, vermiform
2
or fully embryonated stages. Isolation procedures caused similar damage to uterine
and faecal eggs (2.2% and 0.5%, respectively; P=0.180). The first sign of in ovo
embryonic development in faecal eggs (7%) was observed during the 24-hour period
when faeces were collected. On d28, a higher percentage of uterine eggs remained
undeveloped when compared with faecal eggs (58.6% vs 11.0%; P< 0.001).
Although a higher (P<0.001) percentage of faecal eggs entered both the early
developmental and vermiform stages, which took place primarily within the first two
weeks of incubation, there was no time-shift between the development of faecal and
uterine eggs. Starting from d10, higher (P<0.05) percentages of faecal eggs
completed embryonation compared with uterine equivalents.
The second experiment (Paper 2) was demonstrating whether chicks descending
from nematode-infected hens are more resistant against Ascaridia galli, a prevalent
gastrointestinal nematode, infection than infected offspring from nematode-free
mothers. One-day-old chick offspring (N=153) from infected (mab+; maternal
antibody+) or uninfected control dams (mab-) were experimentally infected with A.
galli at two different concentrations (100 or 1000 eggs/chick). Female chickens
exhibited significantly (P<0.05) higher specific antibody concentrations (2.355 ±
0.211). The worm burdens of the chicks were determined at 6 weeks after infection.
There was a high correlation (r=0.89, P<0.001) between A. galli-specific antibody
concentrations in dam plasma and egg yolk. Dam and chick infection doses
interaction had a significant effect (P<0.05) on worm burden and the highest infection
rate (21.2 ± 2.95) occurring in mab+ chicks challenged with +1000 A. galli eggs. In
chicks, lower doses of infection caused a difference in worm burden between the
mab +/ - groups. Chick infection dose had a significant effect on female/ male
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harvested worms. There was also an interaction effect between maternal infection
and chick infection with respect to worm weight.
The final study (Paper 3) was conducted on two genotypes of Brown hens (LB
classic and LB plus) under practical free-range farm condition. Aims of this study
were to describe genetic resistance to immune systems and infectivity diagnosis by
estimating total specific antibody concentration (TsAb) against the most prevalent
nematodes in free-range chicken systems. Chickens (17 weeks old) of two Lohmann
brown genotypes (LB plus/ LB Classic) were examined for a laying period of one and
a half years. Individually obtained plasma of the genotypes, LB plus (n= 200) and LB
classic (n=200) were used for detecting TsAb via the ELISA test before necropsy.
Some birds were subjected to post-mortem parasitological examinations at 79 weeks
(LB plus, n= 162) or 88 weeks (LB classic, n=139) of age. There was a significant
(P<0.05) difference in total worm burden (TWb) and TsAb in relation to the genetic
background of the chickens in their response to naturally acquired nematode
infections. Positive phenotypic correlations (r=0.1, P=0.014) of TsAb with the total
epg (Tepg) before necropsy and no significant correlation (r=-0.13, P=0.1) with TWb
at necropsy were moderated. Slightly fluctuating increases of TsAb by age (weeks)
were observed.
It is concluded that isolated A.galli eggs from both sources reached a plateau of
embryonation by the end of the second week of incubation, with faecal eggs having
more than a two-fold higher embryonation ability. Cumulative mortality was higher in
uterine eggs (14.3%) when compared to faecal eggs (0.2%). Although lower worm
burden in mab- chicks with resistant tendency against A.galli pathogen in maternal
antibody positive (mab+) offspring was demonstrated, no protective immunity against
A. galli infection was observed. In this free-range chicken system, the LB classic
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genotype was more susceptible to gastrointestinal nematodes than the LB plus
genotype with higher total antibody responses before necropsy and lower total
antibody responses at necropsy. Estimating total specific antibody responses is
meaningful for infectivity diagnosis in a free-range chicken system
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
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